Draft California 2020 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name: Little Cottonwood Creek
Water Body ID: CAR6033015020170712054519
Water Body Type: River & Stream
 
DECISION ID
102786
Region 6     
Little Cottonwood Creek
 
Pollutant: Indicator Bacteria
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 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.

Four lines of evidence, two which assess E. coli data for the REC-1 beneficial use and two which assess fecal coliform data for the MUN beneficial use, are available in the administrative record to assess this pollutant. 0 of 17 E. coli geometric mean samples and 0 of 10 E. coli Statistical Threshold Value (STV) samples exceed the water quality objective for the REC-1 beneficial use; 0 of 36 fecal coliform log-mean samples and 0 of 10 fecal coliform STV samples exceed the objective for the MUN beneficial use.

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 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 17 E. coli geometric mean samples and 0 of 10 E. coli Statistical Threshold Value (STV) samples exceed the water quality objective for the REC-1 beneficial use; 0 of 36 fecal coliform log-mean samples and 0 of 10 fecal coliform STV samples exceed the objective for the MUN beneficial use. 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.
 
Regional Board 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.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation:
 
 
Line of Evidence (LOE) for Decision ID 102786, Indicator Bacteria
Region 6     
Little Cottonwood Creek
 
LOE ID: 129431
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 10
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 Little Cottonwood Creek to determine beneficial use support and the results are as follows: 0 of the 10 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 1 monitoring site(s), station(s): 603LCCB01
Temporal Representation: The samples were collected between the days of 2011-07-27 and 2012-10-09 .
Environmental Conditions:
QAPP Information: Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program
QAPP Information Reference(s): Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program
 
Line of Evidence (LOE) for Decision ID 102786, Indicator Bacteria
Region 6     
Little Cottonwood Creek
 
LOE ID: 129481
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 36
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 Little Cottonwood Creek to determine beneficial use support and the results are as follows: 0 of the 36 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 1 monitoring site(s), station(s): 603LCCB01
Temporal Representation: The samples were collected between the days of 2011-07-27 and 2012-10-09 .
Environmental Conditions:
QAPP Information: Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program
QAPP Information Reference(s): Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program
 
Line of Evidence (LOE) for Decision ID 102786, Indicator Bacteria
Region 6     
Little Cottonwood Creek
 
LOE ID: 99786
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 10
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 Little Cottonwood Creek to determine beneficial use support and the results are as follows: 0 of the 10 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 1 monitoring site(s), station(s): 603LCCB01
Temporal Representation: The samples were collected between the days of 2011-07-27 and 2012-10-09 .
Environmental Conditions:
QAPP Information: Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program
QAPP Information Reference(s): Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program
 
Line of Evidence (LOE) for Decision ID 102786, Indicator Bacteria
Region 6     
Little Cottonwood Creek
 
LOE ID: 99745
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 17
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 Little Cottonwood Creek to determine beneficial use support and the results are as follows: 0 of the 17 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 1 monitoring site(s), station(s): 603LCCB01
Temporal Representation: The samples were collected between the days of 2011-07-27 and 2012-10-09 .
Environmental Conditions:
QAPP Information: Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program
QAPP Information Reference(s): Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program