# Draft 2008 California 303(d)/305(b) Integrated Report

# Supporting Information

## Regional Board 3 - Central Coast Region

Water Body Name: | Watsonville Slough
Water Body ID: | CAR3051003019981209150043
Water Body Type: | River & Stream

DECISION ID | 10519
Pollutant: | Ammonia (Unionized)
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the General water quality objective as it is applied to aquatic life beneficial uses. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the 14 samples exceed the General water quality objective as it is applied to aquatic life beneficial uses, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 10519

LOE ID: | 13674
Pollutant: | Ammonia (Unionized)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPNorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Ammonia as N, Unionized.
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin General Objective, Chapter III, Section II.A.2 (General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries) states that the discharge of wastes shall not cause concentrations of unionized ammonia (NH3) to exceed 0.025 mg/l (as N) in receiving waters (page III-4) .
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-3/28/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 9404
Pollutant: | Ammonia (Unionized)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 12 samples exceed the criterion for Ammonia as N, Unionized.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin General Objective, Chapter III, Section II.A.2 (General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries) states that the discharge of wastes shall not cause concentrations of unionized ammonia (NH3) to exceed 0.025 mg/l (as N) in receiving waters (page III-4) .
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):

DECISION ID | 12088
Pollutant: | Chlorophyll-a
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the 16 samples exceed the Evaluation Guideline (North Carolina Administrative code, Title 15A) and the General Water Quality Objective set to protect aquatic life beneficial uses. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. However, there are an insufficient number of samples to make a "use rating" decision. Central Coast Water Board staff require a minimum of 26 samples to make a "use rating" decision of Fully Supporting. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the 16 samples exceed the Evaluation Guideline (North Carolina Administrative code, Title 15A) and the General Water Quality Objective set to protect aquatic life beneficial uses and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 12088

LOE ID: | 9405
Pollutant: | Chlorophyll-a
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 11
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 11 samples exceed the criterion for Chlorophyll a.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect beneficial uses (general objective for biostimulatory substances, Water Quality Control Plan, Central Coast Basin, Chapter III, Section II).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
| North Carolina standards, criteria, or toxic concentrations. Adopted per title 15A North Carolina Administrative Code subchapter 2B - Surface water and wetland standards
| Water quality standards table
Evaluation Guideline: | North Carolina Administrative code (NCAC), Title 15A - Environmental and Natural Resources, Subchapter 2B-Surface water and wetland standards, Rule 0211-Fresh surface water quality standards for class C waters (Class C is defined as freshwaters protected for secondary recreation, fishing, aquatic life including propagation and survival, and wildlife). Section 3(a) of Rule 0211 applies to all fresh surface waters and states that chlorophyll a is not to exceed 40 ug/L.
Guideline Reference: | North Carolina standards, criteria, or toxic concentrations. Adopted per title 15A North Carolina Administrative Code subchapter 2B - Surface water and wetland standards
| North Carolina standards, criteria, or toxic concentrations. Adopted per title 15A North Carolina Administrative Code subchapter 2B - Surface water and wetland standards
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 13689
Pollutant: | Chlorophyll-a
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPNorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for Chlorophyll a.
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect beneficial uses (general objective for biostimulatory substances, Water Quality Control Plan, Central Coast Basin, Chapter III, Section II).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
| North Carolina standards, criteria, or toxic concentrations. Adopted per title 15A North Carolina Administrative Code subchapter 2B - Surface water and wetland standards
| Water quality standards table
Evaluation Guideline: | North Carolina Administrative code (NCAC), Title 15A - Environmental and Natural Resources, Subchapter 2B-Surface water and wetland standards, Rule 0211-Fresh surface water quality standards for class C waters (Class C is defined as freshwaters protected for secondary recreation, fishing, aquatic life including propagation and survival, and wildlife). Section 3(a) of Rule 0211 applies to all fresh surface waters and states that chlorophyll a is not to exceed 40 ug/L.
Guideline Reference: | North Carolina standards, criteria, or toxic concentrations. Adopted per title 15A North Carolina Administrative Code subchapter 2B - Surface water and wetland standards
| North Carolina standards, criteria, or toxic concentrations. Adopted per title 15A North Carolina Administrative Code subchapter 2B - Surface water and wetland standards
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):

DECISION ID | 15875
Pollutant: | Chlorpyrifos
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. None of the 5 samples exceed the Evaluation Guideline (Sipmann and Finlayson, 2000) applied to protect for aquatic life beneficial uses. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. However, there are an insufficient number of samples to make a "use rating" decision. Central Coast Water Board staff require a minimum of 16 samples to make a "use rating" decision of Fully Supporting. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the 5 samples exceed the Evaluation Guideline (Sipmann and Finlayson, 2000) applied to protect for aquatic life beneficial uses and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 15875

LOE ID: | 16007
Pollutant: | Chlorpyrifos
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP_SWAMP Monitoring (04SW3001) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chlorpyrifos.
Data Reference: | Final Data File used for assessment: SWAMP Toxicity Data 2001-06
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
| Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | One hour average maximum concentration 0.025 ug/L as stated in Sipmann and Finlayson (2000).
Guideline Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA001 - Watsonville Slough above pump station at San Andreas]
Temporal Representation: | Data was collected on a single day 5/3/2006. SWAMP toxicity monitoring includes both water samples (collected in both winter and summer) and sediment samples (collected in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 16330
Pollutant: | Chlorpyrifos
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP_SWAMP Monitoring (04SW3001) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Chlorpyrifos.
Data Reference: | Final Data File used for assessment: SWAMP Toxicity Data 2001-06
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
| Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | One hour average maximum concentration 0.025 ug/L as stated in Sipmann and Finlayson (2000).
Guideline Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA001 - Watsonville Slough above pump station at San Andreas]
Temporal Representation: | Data was collected over the time period 1/12/2006-5/30/2006. SWAMP toxicity monitoring includes both water samples (collected in both winter and summer) and sediment samples (collected in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 18601
Pollutant: | Chlorpyrifos
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Department of Health Services (R3_DHS1) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for chlorpyrifos.
Data Reference: | Final Data File used for assessment: DHS Sediment Chemistry Data, File 1 (feb06)
| Final Data File used for assessment: DHS Sediment Chemistry Data, File 2 (sed06)
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
| Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | One hour average maximum concentration 0.025 ug/L as stated in Sipmann and Finlayson (2000).
Guideline Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA_DHS - Watsonville Slough]
Temporal Representation: | Data was collected over the time period 12/13/1994-1/27/1995.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | No QAPP was provided for this data set.
QAPP Information Reference(s):

DECISION ID | 15876
Pollutant: | Diazinon
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. None of the 5 samples exceed the Evaluation Guideline (Sipmann and Finlayson, 2000) applied to protect for aquatic life beneficial uses. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. However, there are an insufficient number of samples to make a "use rating" decision. Central Coast Water Board staff require a minimum of 16 samples to make a "use rating" decision of Fully Supporting. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the 5 samples exceed the Evaluation Guideline (Sipmann and Finlayson, 2000) applied to protect for aquatic life beneficial uses and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 15876

LOE ID: | 16753
Pollutant: | Diazinon
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP_SWAMP Monitoring (04SW3001) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Diazinon.
Data Reference: | Final Data File used for assessment: SWAMP Toxicity Data 2001-06
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
| Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | One hour average maximum concentration 0.16 ug/L as stated in Sipmann and Finlayson (2000).
Guideline Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA001 - Watsonville Slough above pump station at San Andreas]
Temporal Representation: | Data was collected over the time period 1/12/2006-5/30/2006. SWAMP toxicity monitoring includes both water samples (collected in both winter and summer) and sediment samples (collected in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 16659
Pollutant: | Diazinon
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP_SWAMP Monitoring (04SW3001) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Diazinon.
Data Reference: | Final Data File used for assessment: SWAMP Toxicity Data 2001-06
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
| Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | One hour average maximum concentration 0.16 ug/L as stated in Sipmann and Finlayson (2000).
Guideline Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA001 - Watsonville Slough above pump station at San Andreas]
Temporal Representation: | Data was collected on a single day 5/3/2006. SWAMP toxicity monitoring includes both water samples (collected in both winter and summer) and sediment samples (collected in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 18695
Pollutant: | Diazinon
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Department of Health Services (R3_DHS1) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for diazinon.
Data Reference: | Final Data File used for assessment: DHS Sediment Chemistry Data, File 1 (feb06)
| Final Data File used for assessment: DHS Sediment Chemistry Data, File 2 (sed06)
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
| Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | One hour average maximum concentration 0.16 ug/L as stated in Sipmann and Finlayson (2000).
Guideline Reference: | Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA_DHS - Watsonville Slough]
Temporal Representation: | Data was collected over the time period 12/13/1994-1/27/1995.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | No QAPP was provided for this data set.
QAPP Information Reference(s):

DECISION ID | 12965
Pollutant: | Sediment Toxicity
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 and section 3.6 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant in sediment samples. One of the 2 samples were toxic to invertebrate test organisms (did nto exhibit a significant increase in mortality compared to the laboratory control) and therefore does not exceed the narrative General Objective for toxicity, set to protect for aquatic life beneficial uses. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. However, there are an insufficient number of samples to make a "use rating" decision. Central Coast Water Board staff require a minimum of 16 samples to make a "use rating" decision of Fully Supporting, only two toxicity samples are assessed here. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of the 2 samples were toxic to invertebrate test organisms (did nto exibit a significant increase in mortality compared to the laboratory control) and therefore does not exceed the narrative General Objective for toxicity, set to protect for aquatic life beneficial uses and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 12965

LOE ID: | 24701
Pollutant: | Invertebrate Toxicity
LOE Subgroup: | Toxicity
Matrix: | Sediment
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPnorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Toxicity, Hyalella azteca Survival (%) 10 days. Toxicity is defined by SWAMP (2004) as follows: Significant toxicity in the survival endpoint when compared to the negative control based on a statistical test with alpha of less than 5%, and less than the evaluation threshold (both criteria are met).
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, toxicity bioassays of appropriate duration, or other appropriate methods as specified by the Regional Board (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Significant reduction of survival of test organism relative to the control (alpha < 0.05) and test organism survival is 20% less than the control survival.
Guideline Reference: | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected on a single day 5/19/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 24702
Pollutant: | Invertebrate Toxicity
LOE Subgroup: | Toxicity
Matrix: | Sediment
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP_SWAMP Monitoring (04SW3001) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 1 samples exceed the criterion for Toxicity, Hyalella azteca Survival (%) 10 days. Toxicity is defined by SWAMP (2004) as follows: Significant toxicity in the survival endpoint when compared to the negative control based on a statistical test with alpha of less than 5%, and less than the evaluation threshold (both criteria are met).
Data Reference: | Final Data File used for assessment: SWAMP Toxicity Data 2001-06
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, toxicity bioassays of appropriate duration, or other appropriate methods as specified by the Regional Board (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Significant reduction of survival of test organism relative to the control (alpha < 0.05) and test organism survival is 20% less than the control survival.
Guideline Reference: | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA001 - Watsonville Slough above pump station at San Andreas]
Temporal Representation: | Data was collected on a single day 5/3/2006. SWAMP toxicity monitoring includes both water samples (collected in both winter and summer) and sediment samples (collected in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):

DECISION ID | 5519
Pollutant: | Sedimentation/Siltation
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Delist from 303(d) list (TMDL required list)(2006)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for delisting under sections 4.9 of the Listing Policy. Under section 4.9, a minimum of two lines of evidence are needed to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. No data is presented to show impacts or lack of impacts on aquatic life populations or communities. Suspended solids concentrations are well below the level that may impact at least one species present in Watsonville Slough. Visual assessment of sedimentation did not reveal any probable impacts. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of removing this water segment-pollutant combination from the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The guideline used complies generally with the requirements of section 6.1.3 of the Policy. 2. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 3. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 4. None of the 338 samples exceeded the evaluation guideline. No data are available to show impacts on aquatic life. 5. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
RWQCB Board Decision / Staff Recommendation: | No new data were assessed for 2008. The decision has not changed.
SWRCB Board Decision / Staff Recommendation: | After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should be removed from the section 303(d) list because applicable water quality standards for the pollutant are not exceeded
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 5519

LOE ID: | 1855
Pollutant: | Sedimentation/Siltation
LOE Subgroup: | Narrative Description Data
Matrix: | Not Specified
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Long-term aggregation of sediments and reduction in aquatic habitat volume was not evident. Aquatic habitat volume appears to be increasing due to land subsidence associated with de-watering of the area for peat mining and agriculture in the early 1900s, ground water pumping, and possibly local seismic activity. Scientists re-surveyed an old road survey across Struve Slough and Watsonville Slough, and found evidence of subsidence on the order of 10 to 20 mm/year since 1952. Obtained sediment cores in the tidal marsh of lower Watsonville Slough dating back to the 1400s and they were analyzed using radiocarbon dating, pollen, and lead-210. The data suggested an anthropogenic increase in sedimentation surrounding the expansion of agriculture in the first half of the 1900s, but net sedimentation rates since about 1950 appear to have been lower than in pre-historic times. This is likely attributed to decreased sediment supply to the lower reaches resulting from subsidence and the construction of the tide gates in the 1940s (Hager, J. and F. Watson 2005).
Data Reference: | Placeholder reference 2006 303(d)
Water Quality Objective/Criterion: | Basin Plan: The suspended sediment load and suspended sediment discharge rate of surface waters shall not be altered in such a manner as to cause nuisance or adversely affect surface waters.
Objective/Criterion Reference: | Placeholder reference 2006 303(d)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: |
Temporal Representation: |
Environmental Conditions: |
QAPP Information: | Most of the data were collected under a Quality Assurance Project Plan prepared by Central Coast Watershed Studies, The Watershed Institute at California State University Monterey Bay.
QAPP Information Reference(s):
LOE ID: | 1854
Pollutant: | Sedimentation/Siltation
LOE Subgroup: | Narrative Description Data
Matrix: | Not Specified
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Smothering of benthic habitat by sedimentation was not significantly evident, but was also difficult to study. A visual reconnaissance was conducted for signs of excessive recent sedimentation. Unequivocal smothering of habitat could only be documented photographically in small portions of the Watsonville Slough system. Other areas were either stable, contained coarse sediment, contained fine sediment in amounts that did not contradict the expectation of a natural system, were under water, or were not accessible (Hager, J. and F. Watson 2005).
Data Reference: | Placeholder reference 2006 303(d)
Water Quality Objective/Criterion: | Basin Plan: The suspended sediment load and suspended sediment discharge rate of surface waters shall not be altered in such a manner as to cause nuisance or adversely affect surface waters.
Objective/Criterion Reference: | Placeholder reference 2006 303(d)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: |
Temporal Representation: |
Environmental Conditions: |
QAPP Information: | Most of the data were collected under a Quality Assurance Project Plan prepared by Central Coast Watershed Studies, The Watershed Institute at California State University Monterey Bay.
QAPP Information Reference(s):
LOE ID: | 1856
Pollutant: | Sedimentation/Siltation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 338
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Sediment concentration has been studied by many investigators. All available data was reviewed and summarized by (Hager, J. and F. Watson 2005). For suspended sediment concentration, 338 representative measurements are available. None of the measurements exceed the sediment threshold.
Data Reference: | Placeholder reference 2006 303(d)
Water Quality Objective/Criterion: | Basin Plan: The suspended sediment load and suspended sediment discharge rate of surface waters shall not be altered in such a manner as to cause nuisance or adversely affect surface waters.
Objective/Criterion Reference: | Placeholder reference 2006 303(d)
Evaluation Guideline: | Three spine stickleback occurs in the Slough and in studies no mortality was observed in a test to identify the lethal threshold for sediment at a concentration of 28,000 mg/L (LeGore and Des Voigne, 1973).
Guideline Reference: | Placeholder reference 2006 303(d)
Spatial Representation: | Samples were collected at least 13 stations throughout the slough system.
Temporal Representation: | Samples were collected between 1976 and 2004 during all seasons.
Environmental Conditions: |
QAPP Information: | Most of the data were collected under a Quality Assurance Project Plan prepared by Central Coast Watershed Studies, The Watershed Institute at California State University Monterey Bay.
QAPP Information Reference(s):

DECISION ID | 10522
Pollutant: | Total Coliform
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under sections 2.1 and 3.3 of the Listing Policy. However, on July 19, 2007 USEPA amended the water quality standards for Watsonville Slough and its tributaries by removing Shellfish Harvesting as a designated use. Concurrent with the submitted Pathogen TMDL, staff submitted a Use Attainability Analysis (UAA) to amend the beneficial use designations. The USEPA approved the UAA on March 28, 2007.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because the beneficial use was removed.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 10522

LOE ID: | 17421
Pollutant: | Total Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Shellfish Harvesting
Number of Samples: | 11
Number of Exceedances: | 10
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Clean streams project) (R3_CLNStrm) data for Watsonville Slough to determine beneficial use support and results are as follows: 10 of 11 samples exceed the criterion for Coliform, Total.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin Shellfish Harvesting objective (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries (page III-12)) states the following: At all areas where shellfish may be harvested for human consumption, the median total coliform concentration throughout the water column for any 30-day period shall not exceed 70 MPN/100mL, not shall more than ten percent of the samples collected during any 30-day period exceed 230 MPN/100mL for a five tube decimal dilution test.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 2 monitoring sites [ 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-21 - Watsonville Slough at Harkins Slough Road]
Temporal Representation: | Data was collected over the time period 5/26/2004-11/8/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Data entry completed by volunteers. Multiple errors were identified in data and were flagged by RB staff (in communication with Clean Streams Program staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 17457
Pollutant: | Total Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Shellfish Harvesting
Number of Samples: | 9
Number of Exceedances: | 9
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Snapshot day monitoring) (R3_Snap) data for Watsonville Slough to determine beneficial use support and results are as follows: 9 of 9 samples exceed the criterion for Coliform, Total.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin Shellfish Harvesting objective (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries (page III-12)) states the following: At all areas where shellfish may be harvested for human consumption, the median total coliform concentration throughout the water column for any 30-day period shall not exceed 70 MPN/100mL, not shall more than ten percent of the samples collected during any 30-day period exceed 230 MPN/100mL for a five tube decimal dilution test.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/17/2003-5/7/2005. Coastal Watershed Council Snapshot Day Monitoring is conducted annually.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | State Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 11090
Pollutant: | Total Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Shellfish Harvesting
Number of Samples: | 24
Number of Exceedances: | 24
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 24 of 24 samples exceed the criterion for Coliform, Total.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin Shellfish Harvesting objective (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries (page III-12)) states the following: At all areas where shellfish may be harvested for human consumption, the median total coliform concentration throughout the water column for any 30-day period shall not exceed 70 MPN/100mL, not shall more than ten percent of the samples collected during any 30-day period exceed 230 MPN/100mL for a five tube decimal dilution test.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 13813
Pollutant: | Total Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Shellfish Harvesting
Number of Samples: | 57
Number of Exceedances: | 51
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 51 of 57 samples exceed the criterion for Coliform, Total.
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin Shellfish Harvesting objective (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries (page III-12)) states the following: At all areas where shellfish may be harvested for human consumption, the median total coliform concentration throughout the water column for any 30-day period shall not exceed 70 MPN/100mL, not shall more than ten percent of the samples collected during any 30-day period exceed 230 MPN/100mL for a five tube decimal dilution test.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 5 monitoring sites [ Shell Rd at pump station, Pajaro Dunes Colony near confluence with Pajaro R, Lee Rd, San Andreas Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-12/9/2003.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):

DECISION ID | 12078
Pollutant: | Unknown Toxicity
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 and section 3.6 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Six lines of evidence are available in the administrative record to assess this pollutant in water samples. None of the 14 samples were toxic to test organisms (exhibited a significant increase in mortality or a significant decrease in cell density compared to the laboratory control) and therefore does not exceed the narrative General Objective for toxicity, set to protect for aquatic life beneficial uses. The following is a summary of the results from survival toxicity tests. One of the 5 samples (tested for toxicity to plants) exhibited significant reduction in cell density relative to the control. In addition, none of the 5 samples (tested for toxicity to vertebrate test organisms) exhibited a significant increase in mortality compared to the laboratory control. Lastly, none of the 4 samples, tested for toxicity to invertebrate test organisms exhibited a significant increase in mortality compared to the laboratory control. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. However, there are an insufficient number of samples to make a "use rating" decision. Central Coast Water Board staff require a minimum of 16 samples to make a "use rating" decision of Fully Supporting, only 14 toxicity samples are assessed here. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of the samples were toxic to test organisms and therefore does not exceed the narrative General Objective for toxicity, set to protect for aquatic life beneficial uses. and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 12078

LOE ID: | 24713
Pollutant: | Plant Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 3
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPnorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 3 samples exceed the criterion for Toxicity, Selenastrum capricornutum Growth (Cell Density) 4 days. Toxicity is defined by SWAMP (2004) as follows: Significant toxicity in the survival endpoint when compared to the negative control based on a statistical test with alpha of less than 5%, and less than the evaluation threshold (both criteria are met).
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, toxicity bioassays of appropriate duration, or other appropriate methods as specified by the Regional Board (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Significant reduction in cell count of test organism relative to the control (alpha < 0.05) and cell count <80% of control.
Guideline Reference: | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 24691
Pollutant: | Invertebrate Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 3
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPnorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 3 samples exceed the criterion for Toxicity, Ceriodaphnia dubia Survival (%) 7 days. Toxicity is defined by SWAMP (2004) as follows: Significant toxicity in the survival endpoint when compared to the negative control based on a statistical test with alpha of less than 5%, and less than the evaluation threshold (both criteria are met).
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, toxicity bioassays of appropriate duration, or other appropriate methods as specified by the Regional Board (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Significant reduction of survival of test organism relative to the control (alpha < 0.05) and test organism survival is 20% less than the control survival.
Guideline Reference: | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-8/22/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 24708
Pollutant: | Vertebrate Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 3
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPnorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 3 samples exceed the criterion for Toxicity, Pimephales promelas Survival (%) 7 days. Toxicity is defined by SWAMP (2004) as follows: Significant toxicity in the survival endpoint when compared to the negative control based on a statistical test with alpha of less than 5%, and less than the evaluation threshold (both criteria are met).
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, toxicity bioassays of appropriate duration, or other appropriate methods as specified by the Regional Board (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Significant reduction of survival of test organism relative to the control (alpha < 0.05) and test organism survival is 20% less than the control survival.
Guideline Reference: | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 24709
Pollutant: | Vertebrate Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 1
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP_SWAMP Monitoring (04SW3001) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 2 samples exceed the criterion for Toxicity, Pimephales promelas Survival (%) 7 days. Toxicity is defined by SWAMP (2004) as follows: Significant toxicity in the survival endpoint when compared to the negative control based on a statistical test with alpha of less than 5%, and less than the evaluation threshold (both criteria are met).
Data Reference: | Final Data File used for assessment: SWAMP Toxicity Data 2001-06
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, toxicity bioassays of appropriate duration, or other appropriate methods as specified by the Regional Board (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Significant reduction of survival of test organism relative to the control (alpha < 0.05) and test organism survival is 20% less than the control survival.
Guideline Reference: | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA001 - Watsonville Slough above pump station at San Andreas]
Temporal Representation: | Data was collected over the time period 1/12/2006-5/30/2006. SWAMP toxicity monitoring includes both water samples (collected in both winter and summer) and sediment samples (collected in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 24714
Pollutant: | Plant Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP_SWAMP Monitoring (04SW3001) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Toxicity, Selenastrum capricornutum Growth (Cell Density) 4 days. Toxicity is defined by SWAMP (2004) as follows: Significant toxicity in the survival endpoint when compared to the negative control based on a statistical test with alpha of less than 5%, and less than the evaluation threshold (both criteria are met).
Data Reference: | Final Data File used for assessment: SWAMP Toxicity Data 2001-06
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, toxicity bioassays of appropriate duration, or other appropriate methods as specified by the Regional Board (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Significant reduction in cell count of test organism relative to the control (alpha < 0.05) and cell count <80% of control.
Guideline Reference: | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA001 - Watsonville Slough above pump station at San Andreas]
Temporal Representation: | Data was collected over the time period 1/12/2006-5/30/2006. SWAMP toxicity monitoring includes both water samples (collected in both winter and summer) and sediment samples (collected in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 24695
Pollutant: | Invertebrate Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP_SWAMP Monitoring (04SW3001) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Toxicity, Ceriodaphnia dubia Survival (%) 7 days. Toxicity is defined by SWAMP (2004) as follows: Significant toxicity in the survival endpoint when compared to the negative control based on a statistical test with alpha of less than 5%, and less than the evaluation threshold (both criteria are met).
Data Reference: | Final Data File used for assessment: SWAMP Toxicity Data 2001-06
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, toxicity bioassays of appropriate duration, or other appropriate methods as specified by the Regional Board (Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries).
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Significant reduction of survival of test organism relative to the control (alpha < 0.05) and test organism survival is 20% less than the control survival.
Guideline Reference: | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA001 - Watsonville Slough above pump station at San Andreas]
Temporal Representation: | Data was collected over the time period 1/12/2006-5/30/2006. SWAMP toxicity monitoring includes both water samples (collected in both winter and summer) and sediment samples (collected in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):

DECISION ID | 10523
Pollutant: | pH
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Eighteen lines of evidence is available in the administrative record to assess this pollutant. Eighty-two samples exceed the Warm Freshwater Habitat water quality objective and 95 samples exceed the numeric objective for Municipal & Domestic Supply, Non-Contact Recreation and Water Contact Recreation. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Eighty-two of the 1070 samples exceed the Warm Freshwater Habitat water quality objective and 95 of the 1070 samples exceed the numeric objective for Municipal & Domestic Supply, Non-Contact Recreation and Water Contact Recreation. This does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 10523

LOE ID: | 19148
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 43
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Clean streams project) (R3_CLNStrm) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 43 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for water contact recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/13/2004-11/12/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Data entry completed by volunteers. Multiple errors were identified in data and were flagged by RB staff (in communication with Clean Streams Program staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 19150
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 43
Number of Exceedances: | 5
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Clean streams project) (R3_CLNStrm) data for Watsonville Slough to determine beneficial use support and results are as follows: 5 of 43 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, the pH value shall not be depressed below 7.0 or raised above 8.5.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/13/2004-11/12/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Data entry completed by volunteers. Multiple errors were identified in data and were flagged by RB staff (in communication with Clean Streams Program staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 19149
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 43
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Clean streams project) (R3_CLNStrm) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 43 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/13/2004-11/12/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Data entry completed by volunteers. Multiple errors were identified in data and were flagged by RB staff (in communication with Clean Streams Program staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 18914
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 12
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Snapshot day monitoring) (R3_Snap) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 12 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/17/2003-5/6/2006. Coastal Watershed Council Snapshot Day Monitoring is conducted annually.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | State Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 18915
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Snapshot day monitoring) (R3_Snap) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 12 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, the pH value shall not be depressed below 7.0 or raised above 8.5.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/17/2003-5/6/2006. Coastal Watershed Council Snapshot Day Monitoring is conducted annually.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | State Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 11107
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 12 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for water contact recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 11108
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 12 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 11109
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 2
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 2 of 12 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, the pH value shall not be depressed below 7.0 or raised above 8.5.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 13692
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPNorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for water contact recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 13851
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 90
Number of Exceedances: | 9
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 9 of 90 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for water contact recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 6 monitoring sites [ Shell Rd at pump station, Pajaro Dunes Colony near confluence with Pajaro R, Lee Rd, Errington Rd, San Andreas Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-3/1/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):
LOE ID: | 13852
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 90
Number of Exceedances: | 9
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 9 of 90 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 6 monitoring sites [ Shell Rd at pump station, Pajaro Dunes Colony near confluence with Pajaro R, Lee Rd, Errington Rd, San Andreas Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-3/1/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):
LOE ID: | 13725
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPNorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 13726
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPNorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, the pH value shall not be depressed below 7.0 or raised above 8.5.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 13853
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 90
Number of Exceedances: | 8
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 8 of 90 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, the pH value shall not be depressed below 7.0 or raised above 8.5.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 6 monitoring sites [ Shell Rd at pump station, Pajaro Dunes Colony near confluence with Pajaro R, Lee Rd, Errington Rd, San Andreas Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-3/1/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):
LOE ID: | 17612
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 908
Number of Exceedances: | 84
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Monterey Area Research Consortium (R3_MARC) data for Watsonville Slough to determine beneficial use support and results are as follows: 84 of 908 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Marc Los Huertos Water Quality Data, file A
| Final Data File used for assessment: Marc Los Huertos Water Quality Data, file B
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for water contact recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 8 monitoring sites [ WS-LEE - Watsonville Slough at Lee, WS-SAR - Watsonville Slough at San Andreas Road, WS-SHA - Watsonville Slough above Shell Road, WS-SHB - Watsonville Slough below Shell Road, WS-ERR - Watsonville Slough at Errington, Krausse confluence, Krausse ditch w/ willows, Krausse open water]
Temporal Representation: | Data was collected over the time period 10/4/2000-2/6/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 17613
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 908
Number of Exceedances: | 84
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Monterey Area Research Consortium (R3_MARC) data for Watsonville Slough to determine beneficial use support and results are as follows: 84 of 908 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Marc Los Huertos Water Quality Data, file A
| Final Data File used for assessment: Marc Los Huertos Water Quality Data, file B
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 8 monitoring sites [ WS-LEE - Watsonville Slough at Lee, WS-SAR - Watsonville Slough at San Andreas Road, WS-SHA - Watsonville Slough above Shell Road, WS-SHB - Watsonville Slough below Shell Road, WS-ERR - Watsonville Slough at Errington, Krausse confluence, Krausse ditch w/ willows, Krausse open water]
Temporal Representation: | Data was collected over the time period 10/4/2000-2/6/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 17614
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 908
Number of Exceedances: | 67
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Monterey Area Research Consortium (R3_MARC) data for Watsonville Slough to determine beneficial use support and results are as follows: 67 of 908 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Marc Los Huertos Water Quality Data, file A
| Final Data File used for assessment: Marc Los Huertos Water Quality Data, file B
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, the pH value shall not be depressed below 7.0 or raised above 8.5.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 8 monitoring sites [ WS-LEE - Watsonville Slough at Lee, WS-SAR - Watsonville Slough at San Andreas Road, WS-SHA - Watsonville Slough above Shell Road, WS-SHB - Watsonville Slough below Shell Road, WS-ERR - Watsonville Slough at Errington, Krausse confluence, Krausse ditch w/ willows, Krausse open water]
Temporal Representation: | Data was collected over the time period 10/4/2000-2/6/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 18897
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 12
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Snapshot day monitoring) (R3_Snap) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 12 samples exceed the criterion for pH.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for water contact recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: pH value shall neither be depressed below 6.5 nor raised above 8.3.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/17/2003-5/6/2006. Coastal Watershed Council Snapshot Day Monitoring is conducted annually.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | State Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):

DECISION ID | 10521
Pollutant: | Low Dissolved Oxygen
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture | Removal of Riparian Vegetation | Urban Runoff/Storm Sewers
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under sections 2.1 and 3.2 of the Listing Policy. Five lines of evidence are available in the administrative record to assess this pollutant. Based on section 3.2 the site exceeded numeric objectives for conventional pollutants. According to the binomial distribution, waters shall be placed on the section 303(d) list if the number of measured exceedances supports rejection of the null hypothesis as presented in Table 3.2. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Eighteen of 20 samples exceed the General Objective for oxygen saturation and 362 of 937 samples exceeded the Warn Freshwater Habitat water quality objective or dissolved oxygen. Each of these exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 10521

LOE ID: | 17855
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 868
Number of Exceedances: | 324
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Monterey Area Research Consortium (R3_MARC) data for Watsonville Slough to determine beneficial use support and results are as follows: 324 of 868 samples exceed the criterion for Oxygen, Dissolved.
Data Reference: | Final Data File used for assessment: Marc Los Huertos Water Quality Data, file A
| Final Data File used for assessment: Marc Los Huertos Water Quality Data, file B
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, dissolved oxygen concentration shall not be reduced below 5.0 mg/l at any time.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 8 monitoring sites [ WS-LEE - Watsonville Slough at Lee, WS-SAR - Watsonville Slough at San Andreas Road, WS-SHA - Watsonville Slough above Shell Road, WS-SHB - Watsonville Slough below Shell Road, WS-ERR - Watsonville Slough at Errington, Krausse confluence, Krausse ditch w/ willows, Krausse open water]
Temporal Representation: | Data was collected over the time period 10/4/2000-2/6/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 18120
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 11
Number of Exceedances: | 3
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Snapshot day monitoring) (R3_Snap) data for Watsonville Slough to determine beneficial use support and results are as follows: 3 of 11 samples exceed the criterion for Oxygen, Dissolved.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, dissolved oxygen concentration shall not be reduced below 5.0 mg/l at any time.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/17/2003-5/6/2006. Coastal Watershed Council Snapshot Day Monitoring is conducted annually.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | State Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 18155
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 41
Number of Exceedances: | 27
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Clean streams project) (R3_CLNStrm) data for Watsonville Slough to determine beneficial use support and results are as follows: 27 of 41 samples exceed the criterion for Oxygen, Dissolved.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, dissolved oxygen concentration shall not be reduced below 5.0 mg/l at any time.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/13/2004-11/12/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Data entry completed by volunteers. Multiple errors were identified in data and were flagged by RB staff (in communication with Clean Streams Program staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 17895
Pollutant: | Dissolved oxygen saturation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 3
Number of Exceedances: | 3
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Monterey Area Research Consortium (R3_MARC) data for Watsonville Slough to determine beneficial use support and results are as follows: 3 of 3 samples exceed the criterion for Oxygen, Saturation.
Data Reference: | Final Data File used for assessment: Marc Los Huertos Water Quality Data, file A
| Final Data File used for assessment: Marc Los Huertos Water Quality Data, file B
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: Median values should not fall below 85% saturation as a result of controllable water quality conditions.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 2 monitoring sites [ WS-LEE - Watsonville Slough at Lee, WS-SHB - Watsonville Slough below Shell Road]
Temporal Representation: | Data was collected over the time period 10/5/2004-2/21/2006.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 13691
Pollutant: | Dissolved oxygen saturation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 5
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPNorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 5 of 5 samples exceed the criterion for Oxygen, Saturation.
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: Median values should not fall below 85% saturation as a result of controllable water quality conditions.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 12019
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 5
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 5 of 12 samples exceed the criterion for Oxygen, Dissolved.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, dissolved oxygen concentration shall not be reduced below 5.0 mg/l at any time.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 12020
Pollutant: | Dissolved oxygen saturation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 10
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 10 of 12 samples exceed the criterion for Oxygen, Saturation.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: Median values should not fall below 85% saturation as a result of controllable water quality conditions.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 13690
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 3
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPNorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 3 of 5 samples exceed the criterion for Oxygen, Dissolved.
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | Water Quality Control Plan, Central Coast Basin, General Objective, Chapter III, Section II.A.2 General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, dissolved oxygen concentration shall not be reduced below 5.0 mg/l at any time.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):

DECISION ID | 12086
Pollutant: | Turbidity
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture | Removal of Riparian Vegetation | Urban Runoff/Storm Sewers
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under sections 2.1 and 3.2 of the Listing Policy. Four lines of evidence are available in the administrative record to assess this pollutant. Based on section 3.2 the site exceeded numeric objectives for conventional pollutants. According to the binomial distribution, waters shall be placed on the section 303(d) list if the number of measured exceedances supports rejection of the null hypothesis as presented in Table 3.2. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This Evaluation Guideline is relevant for Watsonville Slough as it is a tributary to the lowest reaches of the Pajaro River. A recent publication (Steelhead/Rainbow Trout (Oncorhynchus mykiss) Resources South of the Golden Gate, California (Becker, G.S and I.J Reining, October 2008) identifies Pajaro River as having "Definite run or population". Therefore, discharge of turbid water from Watsonville Slough is specifically prohibited by the General Objectives in the Central Coast Water Quality Control Plan which states that waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One hundred ninty-one of 262 samples exceeded the Evaluation Guideline (Sigler et al., 1984) applied to protect for aquatic life beneficial uses and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 12086

LOE ID: | 13727
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 3
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCWQP Northern Area Ag-Waiver Monitoring (R3_CMPNorth) data for Watsonville Slough to determine beneficial use support and results are as follows: 3 of 5 samples exceed the criterion for Turbidity(NTU).
Data Reference: | Final Data File used for assessment: Central Coast Water Quality Preservation Inc toxicity data
| Final Data File used for assessment: Central Coast Water Quality Preservation Inc water quality data
Water Quality Objective/Criterion: | Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses. Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Sigler et al. (1984) states that turbidities of 25 NTU's or greater caused reduction in juvenile salmonid growth due to interference with their ability to find food.
Guideline Reference: | Effects of chronic turbidity on density and growth of steelheads and coho salmon. Transactions of the American Fisheries Society 113:142-150
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 2/21/2006-9/26/2006. Cooperative Monitoring Program (CMP) staff conduct monitoring for conventional pollutants at all Ag Waiver monitoring sites monthly. CMP staff also conduct water toxicity monitoring quarterly and sediment toxicity monitoring annually (in spring).
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the Cooperative Monitoring Program QAPP, (Clark and Ogle 2006). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 12021
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 8
Number of Exceedances: | 6
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 6 of 8 samples exceed the criterion for Turbidity(NTU).
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses. Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Sigler et al. (1984) states that turbidities of 25 NTU's or greater caused reduction in juvenile salmonid growth due to interference with their ability to find food.
Guideline Reference: | Effects of chronic turbidity on density and growth of steelheads and coho salmon. Transactions of the American Fisheries Society 113:142-150
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 7/21/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 13698
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 93
Number of Exceedances: | 39
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 39 of 93 samples exceed the criterion for Turbidity(NTU).
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses. Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Sigler et al. (1984) states that turbidities of 25 NTU's or greater caused reduction in juvenile salmonid growth due to interference with their ability to find food.
Guideline Reference: | Effects of chronic turbidity on density and growth of steelheads and coho salmon. Transactions of the American Fisheries Society 113:142-150
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 6 monitoring sites [ Shell Rd at pump station, Lee Rd, San Andreas Rd, Pajaro Dunes Colony near confluence with Pajaro R, Errington Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-3/1/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):
LOE ID: | 17542
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 156
Number of Exceedances: | 143
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Monterey Area Research Consortium (R3_MARC) data for Watsonville Slough to determine beneficial use support and results are as follows: 143 of 156 samples exceed the criterion for Turbidity(NTU).
Data Reference: | Final Data File used for assessment: Marc Los Huertos Water Quality Data, file A
| Final Data File used for assessment: Marc Los Huertos Water Quality Data, file B
Water Quality Objective/Criterion: | Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses. Water Quality Control Plan, Central Coast Basin, Chapter III, Section II.A.2 Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: | Sigler et al. (1984) states that turbidities of 25 NTU's or greater caused reduction in juvenile salmonid growth due to interference with their ability to find food.
Guideline Reference: | Effects of chronic turbidity on density and growth of steelheads and coho salmon. Transactions of the American Fisheries Society 113:142-150
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 5 monitoring sites [ WS-LEE - Watsonville Slough at Lee, WS-SAR - Watsonville Slough at San Andreas Road, WS-SHB - Watsonville Slough below Shell Road, WS-SHA - Watsonville Slough above Shell Road, WS-ERR - Watsonville Slough at Errington]
Temporal Representation: | Data was collected over the time period 9/21/2005-2/6/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):

DECISION ID | 15874
Pollutant: | Pathogens
Final Listing Decision: | List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture | Collection System Failure | Grazing-Related Sources | Landfills | Natural Sources | Pasture Grazing-Riparian and/or Upland | Urban Runoff/Storm Sewers
TMDL Name: | Watsonville Slough Pathogen
TMDL Project Code: | 35
Date TMDL Approved by USEPA: | 07/19/2007
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | A TMDL has been approved by USEPA (July 19, 2007) for pathogens in Watsonville Slough and four of its tributaries. This pollutant is being considered for removal from the section 303(d) list under section 4.3 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Thirteen lines of evidence are available in the administrative record to assess this pollutant. One LOE #1857 is a placeholder for the listing made prior to 2006. Although the original data and assessment are not available to amend this line of evidence, more recent data for Fecal Coliform and E. coli support the decision to list the water segment-pollutant combination. Forty-five of 89 E. coli samples exceed Evaluation Guideline (USEPA Ambient Water Quality Criteria for Bacteria, 1986) as it applies to the Water Contact Recreation beneficial use and 30 of 69 Fecal Coliform samples exceed the water quality objective for Water Contact Recreation. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the section 303(d) list. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Forty-five of 89 E. coli samples exceed Evaluation Guideline (USEPA Ambient Water Quality Criteria for Bacteria, 1986) as it applies to the Water Contact Recreation beneficial use and 30 of 69 Fecal Coliform samples exceed the water quality objective for Water Contact Recreation. Each of these exceeds the allowable frequency calculated from the equation in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list (being addressed by a USEPA approved TMDL) because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 15874

LOE ID: | 13640
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 57
Number of Exceedances: | 1
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 57 samples exceed the criterion for Escherichia coli.
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 2000/100 ml, nor shall more than ten percent of samples collected during any 30-day period exceed 4000/100 ml. E. coli is a fecal coliform.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 5 monitoring sites [ Shell Rd at pump station, Pajaro Dunes Colony near confluence with Pajaro R, Lee Rd, San Andreas Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-12/9/2003.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):
LOE ID: | 13639
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 57
Number of Exceedances: | 32
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 32 of 57 samples exceed the criterion for Escherichia coli.
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | USEPA Ambient Water Quality Criteria for Bacteria -1986.
Objective/Criterion Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Evaluation Guideline: | Single sample maximum allowable density for E. coli in freshwater is 235 MPN/100mL (as stated in Table 4, page 15)
Guideline Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 5 monitoring sites [ Shell Rd at pump station, Pajaro Dunes Colony near confluence with Pajaro R, Lee Rd, San Andreas Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-12/9/2003.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):
LOE ID: | 18534
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 9
Number of Exceedances: | 2
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Snapshot day monitoring) (R3_Snap) data for Watsonville Slough to determine beneficial use support and results are as follows: 2 of 9 samples exceed the criterion for Escherichia coli.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | USEPA Ambient Water Quality Criteria for Bacteria -1986.
Objective/Criterion Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Evaluation Guideline: | Single sample maximum allowable density for E. coli in freshwater is 235 MPN/100mL (as stated in Table 4, page 15)
Guideline Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/17/2003-5/7/2005. Coastal Watershed Council Snapshot Day Monitoring is conducted annually.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | State Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 18535
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 9
Number of Exceedances: | 2
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Snapshot day monitoring) (R3_Snap) data for Watsonville Slough to determine beneficial use support and results are as follows: 2 of 9 samples exceed the criterion for Escherichia coli.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 2000/100 ml, nor shall more than ten percent of samples collected during any 30-day period exceed 4000/100 ml. E. coli is a fecal coliform.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 3 monitoring sites [ 305-WATSO-21 - Watsonville Slough at Harkins Slough Road, 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-22 - Watsonville Slough at Pajaro Valley Water Management Agency Pump Station]
Temporal Representation: | Data was collected over the time period 5/17/2003-5/7/2005. Coastal Watershed Council Snapshot Day Monitoring is conducted annually.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | State Board approved QAPP. Multiple errors were identified in data and were flagged or fixed by RB staff (in communication with Project staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 18492
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 11
Number of Exceedances: | 7
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Clean streams project) (R3_CLNStrm) data for Watsonville Slough to determine beneficial use support and results are as follows: 7 of 11 samples exceed the criterion for Escherichia coli.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | USEPA Ambient Water Quality Criteria for Bacteria -1986.
Objective/Criterion Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Evaluation Guideline: | Single sample maximum allowable density for E. coli in freshwater is 235 MPN/100mL (as stated in Table 4, page 15)
Guideline Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 2 monitoring sites [ 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-21 - Watsonville Slough at Harkins Slough Road]
Temporal Representation: | Data was collected over the time period 5/26/2004-11/8/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Data entry completed by volunteers. Multiple errors were identified in data and were flagged by RB staff (in communication with Clean Streams Program staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 1857
Pollutant: | Pathogens
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference: | Placeholder reference 2006 303(d)
Water Quality Objective/Criterion: |
Objective/Criterion Reference:
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: |
Temporal Representation: |
Environmental Conditions: |
QAPP Information: | QA Info Missing
QAPP Information Reference(s):
LOE ID: | 11091
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 12
Number of Exceedances: | 4
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 4 of 12 samples exceed the criterion for Escherichia coli.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | USEPA Ambient Water Quality Criteria for Bacteria -1986.
Objective/Criterion Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Evaluation Guideline: | Single sample maximum allowable density for E. coli in freshwater is 235 MPN/100mL (as stated in Table 4, page 15)
Guideline Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 11089
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 12
Number of Exceedances: | 1
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 12 samples exceed the criterion for Coliform, Fecal.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 2000/100 ml, nor shall more than ten percent of samples collected during any 30-day period exceed 4000/100 ml.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 11088
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 12
Number of Exceedances: | 4
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 4 of 12 samples exceed the criterion for Coliform, Fecal.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for water contact recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 200 MPN/100 ml, nor shall more than ten percent of total samples during any 30-day period exceed 400 MPN/100 ml.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 18493
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 11
Number of Exceedances: | 0
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Coastal Watershed Council (Clean streams project) (R3_CLNStrm) data for Watsonville Slough to determine beneficial use support and results are as follows: 0 of 11 samples exceed the criterion for Escherichia coli.
Data Reference: | Final Data File used for assessment: Monterey Bay National Marine Sanctuary Volunteer Monitoring Network Data. 2003-2006
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 2000/100 ml, nor shall more than ten percent of samples collected during any 30-day period exceed 4000/100 ml. E. coli is a fecal coliform.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 2 monitoring sites [ 305-WATSO-23 - Watsonville Slough at Palm Beach Rd., 305-WATSO-21 - Watsonville Slough at Harkins Slough Road]
Temporal Representation: | Data was collected over the time period 5/26/2004-11/8/2004.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Regional Board approved QAPP. Data entry completed by volunteers. Multiple errors were identified in data and were flagged by RB staff (in communication with Clean Streams Program staff) prior to assessment of data.
QAPP Information Reference(s):
LOE ID: | 11092
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 12
Number of Exceedances: | 1
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed CCAMP Pajaro (Pajaro) data for Watsonville Slough to determine beneficial use support and results are as follows: 1 of 12 samples exceed the criterion for Escherichia coli.
Data Reference: | Final Data File used for assessment: CCAMP Water Quality Data_file1
| Final Data File used for assessment: CCAMP Water Quality Data_file2
| Final Data File used for assessment: CCAMP Water Quality Data_file3
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 2000/100 ml, nor shall more than ten percent of samples collected during any 30-day period exceed 4000/100 ml. E. coli is a fecal coliform.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 1 monitoring site [ 305WSA-Watsonville Slough at San Andreas Road]
Temporal Representation: | Data was collected over the time period 1/24/2005-3/16/2006. Pajaro watershed is one of five annual rotation areas that are monitored for conventional pollutants by CCAMP staff monthly for one year.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission. All data are flagged as appropriate.
QAPP Information Reference(s):
LOE ID: | 14057
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Non-Contact Recreation
Number of Samples: | 57
Number of Exceedances: | 5
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 5 of 57 samples exceed the criterion for Coliform, Fecal.
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for non-contact water recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 2000/100 ml, nor shall more than ten percent of samples collected during any 30-day period exceed 4000/100 ml.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 5 monitoring sites [ Shell Rd at pump station, Pajaro Dunes Colony near confluence with Pajaro R, Lee Rd, San Andreas Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-12/9/2003.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):
LOE ID: | 14056
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 57
Number of Exceedances: | 26
Data and Information Type: | PATHOGEN MONITORING
Data Used to Assess Water Quality: | Central Coast Regional Board Staff assessed Central Coast Watershed Studies (R3_CCOWS) data for Watsonville Slough to determine beneficial use support and results are as follows: 26 of 57 samples exceed the criterion for Coliform, Fecal.
Data Reference: | Final Data File used for assessment: CCoWS (Central Coast Watershed Studies) Water Quality Data
Water Quality Objective/Criterion: | The Water Quality Control Plan, Central Coast Basin objective for water contact recreation uses (Section II.A.2. Objectives for All Inland Surface Waters, Enclosed Bays, and Estuaries, II.A.2.a) states the following: Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 200 MPN/100 ml, nor shall more than ten percent of total samples during any 30-day period exceed 400 MPN/100 ml.
Objective/Criterion Reference: | Water Quality Control Plan Central Coast Region (R3) Basin Plan
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for Watsonville Slough was collected at 5 monitoring sites [ Shell Rd at pump station, Pajaro Dunes Colony near confluence with Pajaro R, Lee Rd, San Andreas Rd, Harkins Slough Rd]
Temporal Representation: | Data was collected over the time period 2/18/2003-12/9/2003.
Environmental Conditions: | Staff is not aware of any special conditions that might effect interpretation of the data.
QAPP Information: | Data quality is good and Standard Operating Procedures are well documented in QAPP. However, data documentation is poor and replicate samples and other quality assurance measurements are not consistently documented in this data set.
QAPP Information Reference(s):

DECISION ID | 6934
Pollutant: | Pesticides
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | List on 303(d) list (TMDL required list)(2006)
Revision Status | Original
Sources: | Agriculture | Agriculture-irrigation tailwater | Agriculture-storm runoff | Irrigated Crop Production | Nonpoint Source
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed.
RWQCB Board Decision / Staff Recommendation: | No new data were assessed for 2008. The Regional Board will update this decision when new data and information become available and are assessed.
SWRCB Board Decision / Staff Recommendation: | N/A
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 6934

LOE ID: | 4021
Pollutant: | Pesticides
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Not Recorded
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference: | Placeholder reference pre-2006 303(d)
Water Quality Objective/Criterion: | Unspecified
Objective/Criterion Reference: | Placeholder reference pre-2006 303(d)
Evaluation Guideline: | Unspecified
Guideline Reference: | Placeholder reference pre-2006 303(d)
Spatial Representation: | Unspecified
Temporal Representation: | Unspecified
Environmental Conditions: | Unspecified
QAPP Information: | Unspecified
QAPP Information Reference(s):