| Water Body Name: | Mill Creek (tributary to West Walker River) |
| Water Body ID: | CAR6311002020171206030100 |
| Water Body Type: | River & Stream |
DECISION ID |
103440 |
Region 6 |
Mill Creek (tributary to West Walker River) |
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| Pollutant: | Benthic Community Effects |
| 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 |
| Regional Board Staff Conclusion: | Benthic Community Effects are being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, additional lines of evidence (LOEs) associating the Benthic Community Effects decision with a water or sediment concentration of pollutants other than benthic-macroinvertebrate bioassessment or habitat assessment LOEs are necessary to place a water body on the 303(d) List for Benthic Community Effects.
One line of evidence evaluating benthic-macroinvertebrate bioassessment data is available in the administrative record to assess this indicator. 0 of 5 benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold. These data indicate that the waterbody is likely unimpaired for Benthic Community Effects and therefore no other pollutant LOEs need be associated with this decision at this time. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing Benthic Community Effects in this waterbody segment on the CWA 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. 0 of 5 benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. Therefore, this water body is not exceeding the water quality threshold for the protection of the COLD beneficial use. The available information indicates that the waterbody/pollutant combination should not be placed on the 303(d) List of impaired waters at this time. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. |
| Regional Board Staff Decision 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. |
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| LOE ID: | 96799 | ||||
| Pollutant: | Benthic-Macroinvertebrate Bioassessments | ||||
| LOE Subgroup: | Population/Community Degradation | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 5 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | Not Specified | ||||
| Data Used to Assess Water Quality: | The water body had CSCI scores of 1.067353, 1.119545, 1.182835, 1.1846795 and 1.117025 and is therefore not exceeding the water quality objective for the aquatic life beneficial use. Additionally, this water body passed several screening criteria and was identified as a reference water body for the purposes of developing the CSCI. Reference sites where human disturbance is absent or minimal are used to set benchmark expectations for healthy streams. A large set of nearly 600 reference sites representing the broad diversity of natural stream types found across California was used to develop the CSCI. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Reference Condition Management Plan (RCMP). | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended) | ||||
| Evaluation Guideline: | The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rhen, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use. | ||||
| Guideline Reference: | The California Stream Condition Index (CSCI): A New Statewide Biological Scoring Tool for Assessing the Health of Freshwater Streams. | ||||
| Spatial Representation: | Sample collected at the following station: 631MIL001 and 631CE0074, 601PS0077 | ||||
| Temporal Representation: | Sample Collected on:
7/1/2003 8/19/1999 7/19/2002 8/23/2004 8/7/2012 |
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| Environmental Conditions: | |||||
| QAPP Information: | QAPP for SWAMP Reference Condition Management Plan. | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
DECISION ID |
102502 |
Region 6 |
Mill Creek (tributary to West Walker River) |
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| Pollutant: | Indicator Bacteria |
| Final Listing Decision: | List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | New Decision |
| Revision Status | Revised |
| Sources: | Source Unknown |
| Expected TMDL Completion Date: | 2031 |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Staff Conclusion: | This pollutant is being considered for placement on the CWA 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.
Eight lines of evidence, four which assess the available E. coli data for the REC-1 beneficial use and four which assess the available fecal coliform data for the MUN beneficial use, are available in the administrative record to assess this pollutant. 0 of 6 E. coli geometric mean samples exceed the water quality objective; 0 of 17 E. coli Statistical Threshold Value (STV) samples exceed the objective; 10 of 23 fecal coliform geometric mean samples exceed the objective; 3 of 14 fecal coliform STV samples exceed the objective. 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 CWA 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. 10 of 23 fecal coliform geometric mean samples exceed the water quality objective 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. |
| Regional Board Staff Decision 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. |
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| LOE ID: | 129355 | ||||
| Pollutant: | Fecal Coliform | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Municipal & Domestic Supply | ||||
| Number of Samples: | 5 | ||||
| Number of Exceedances: | 1 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed RWB6_BACT_Monitoring data for Mill Creek (tributary to West Walker River) to determine beneficial use support and the results are as follows: 1 of the 5 samples exceeded the water quality standard for Coliform, Fecal. The water quality standard is based on a 10% exceedance rate that is calculated monthly. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Regional Water Board 6 Bacteria Monitoring. | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. (Lahontan Region Basin Plan) | ||||
| Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 2 monitoring site(s), station(s): 631MIL002, 631MIL008 | ||||
| Temporal Representation: | The samples were collected between the days of 2016-04-12 and 2016-06-14 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
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| LOE ID: | 100049 | ||||
| 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: | 0 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed SWAMP RWB6 Monitoring data for Mill Creek (tributary to West Walker River) to determine beneficial use support and the results are as follows: 0 of the 12 samples exceeded the Statistical Threshold Value (STV) water quality standard for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water). | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The bacteria water quality objective applicable to all waters, except Lake Tahoe, where the salinity is less than 10 parts per thousand (ppth) 95 percent or more of the time is a STATISTICAL THRESHOLD VALUE (STV) of 320 cfu/100 mL not to be exceeded more than 10 percent of the time (calculated monthly). | ||||
| Objective/Criterion Reference: | Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 3 monitoring site(s), station(s): 631MIL002, 631MIL005, 631MIL008 | ||||
| Temporal Representation: | The samples were collected between the days of 2014-08-13 and 2015-10-15 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
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| LOE ID: | 99714 | ||||
| Pollutant: | Escherichia coli (E. coli) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 1 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed RWB6_BACT_Monitoring data for Mill Creek (tributary to West Walker River) to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the geomean water quality standard for E. coli. This is a six week rolling geomean that is calculated weekly. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Regional Water Board 6 Bacteria Monitoring. | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The bacteria water quality objective applicable to all waters, except Lake Tahoe, where the salinity is less than 10 parts per thousand (ppth) 95 percent or more of the time is a six-week rolling GEOMETRIC MEAN (GM) of Escherichia coli (E. coli) not to exceed 100 colony forming units per 100 milliliters (cfu/100 mL) (calculated weekly). | ||||
| Objective/Criterion Reference: | Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 2 monitoring site(s), station(s): 631MIL002, 631MIL008 | ||||
| Temporal Representation: | The samples were collected between the days of 2016-04-12 and 2016-06-14 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
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| LOE ID: | 99824 | ||||
| Pollutant: | Escherichia coli (E. coli) | ||||
| 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: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed SWAMP RWB6 Monitoring data for Mill Creek (tributary to West Walker River) to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the geomean water quality standard for E. coli. This is a six week rolling geomean that is calculated weekly. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water). | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The bacteria water quality objective applicable to all waters, except Lake Tahoe, where the salinity is less than 10 parts per thousand (ppth) 95 percent or more of the time is a six-week rolling GEOMETRIC MEAN (GM) of Escherichia coli (E. coli) not to exceed 100 colony forming units per 100 milliliters (cfu/100 mL) (calculated weekly). | ||||
| Objective/Criterion Reference: | Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 3 monitoring site(s), station(s): 631MIL002, 631MIL005, 631MIL008 | ||||
| Temporal Representation: | The samples were collected between the days of 2014-08-13 and 2015-10-15 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
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| LOE ID: | 129451 | ||||
| Pollutant: | Fecal Coliform | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Municipal & Domestic Supply | ||||
| Number of Samples: | 17 | ||||
| Number of Exceedances: | 8 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed SWAMP RWB6 Monitoring data for Mill Creek (tributary to West Walker River) to determine beneficial use support and the results are as follows: 8 of the 17 samples exceeded the logmean water quality standard for Coliform, Fecal. This is a 30-day rolling logmean that is calculated daily. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water). | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml. (Lahontan Region Basin Plan) | ||||
| Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 3 monitoring site(s), station(s): 631MIL002, 631MIL005, 631MIL008 | ||||
| Temporal Representation: | The samples were collected between the days of 2014-08-13 and 2015-10-15 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
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| LOE ID: | 129416 | ||||
| Pollutant: | Fecal Coliform | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Municipal & Domestic Supply | ||||
| Number of Samples: | 6 | ||||
| Number of Exceedances: | 2 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed RWB6_BACT_Monitoring data for Mill Creek (tributary to West Walker River) to determine beneficial use support and the results are as follows: 2 of the 6 samples exceeded the logmean water quality standard for Coliform, Fecal. This is a 30-day rolling logmean that is calculated daily. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Regional Water Board 6 Bacteria Monitoring. | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml. (Lahontan Region Basin Plan) | ||||
| Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 2 monitoring site(s), station(s): 631MIL002, 631MIL008 | ||||
| Temporal Representation: | The samples were collected between the days of 2016-04-12 and 2016-06-14 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
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| LOE ID: | 99755 | ||||
| Pollutant: | Escherichia coli (E. coli) | ||||
| 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: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed RWB6_BACT_Monitoring data for Mill Creek (tributary to West Walker River) to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the Statistical Threshold Value (STV) water quality standard for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Regional Water Board 6 Bacteria Monitoring. | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The bacteria water quality objective applicable to all waters, except Lake Tahoe, where the salinity is less than 10 parts per thousand (ppth) 95 percent or more of the time is a STATISTICAL THRESHOLD VALUE (STV) of 320 cfu/100 mL not to be exceeded more than 10 percent of the time (calculated monthly). | ||||
| Objective/Criterion Reference: | Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 2 monitoring site(s), station(s): 631MIL002, 631MIL008 | ||||
| Temporal Representation: | The samples were collected between the days of 2016-04-12 and 2016-06-14 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
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| LOE ID: | 129238 | ||||
| Pollutant: | Fecal Coliform | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Municipal & Domestic Supply | ||||
| Number of Samples: | 9 | ||||
| Number of Exceedances: | 2 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Water Board staff assessed SWAMP RWB6 Monitoring data for Mill Creek (tributary to West Walker River) to determine beneficial use support and the results are as follows: 2 of the 9 samples exceeded the water quality standard for Coliform, Fecal. The water quality standard is based on a 10% exceedance rate that is calculated monthly. | ||||
| Data Reference: | Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water). | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. (Lahontan Region Basin Plan) | ||||
| Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected at 3 monitoring site(s), station(s): 631MIL002, 631MIL005, 631MIL008 | ||||
| Temporal Representation: | The samples were collected between the days of 2014-08-13 and 2015-10-15 . | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||
| QAPP Information Reference(s): | Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program | ||||