Draft California 2026 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name: Convict Creek
Water Body ID: CAR6031006020170721053267
Water Body Type: River & Stream
 
DECISION ID
170451
Region 6     
Convict Creek
 
Pollutant: Indicator Bacteria
Final Listing Decision: Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Reason for Delisting: Applicable WQS attained; due to change in WQS
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for removal from the CWA section 303(d) List under section 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 30 samples exceeded the objective. (Fecal coliform lines of evidence used in previous indicator bacteria decisions in the Lahontan Region have been removed from decisions, starting in the 2026 Integrated Report, because the Lahontan Region's fecal coliform objective was removed from the Basin Plan in 2024).


Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for removing this water segment-pollutant combination from 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. Zero of the 30 samples exceeded the objective, and this does not exceed the allowable frequency listed 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 not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB 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 being exceeded.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation:
 
 
Line of Evidence (LOE) for Decision ID 170451, Indicator Bacteria
Region 6     
Convict Creek
 
LOE ID: 99963
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 30
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Eastern Sierra Ambient Monitoring data for Convict Creek to determine beneficial use support and the results are as follows: 0 of the 30 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 Eastern Sierra Ambient Monitoring.
 
SWAMP Data: Non-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 5 monitoring site(s), station(s): CON.10, CON.15, CON.20, CON.30, CON.40
Temporal Representation: The samples were collected between the days of 2012-07-25 and 2013-10-17 .
Environmental Conditions:
QAPP Information: Quality Assurance Project Plan Sierra Nevada Aquatic Research Laboratory Center for Eastern Sierra Aquatic Microbial Ecology
QAPP Information Reference(s): Quality Assurance Project Plan Sierra Nevada Aquatic Research Laboratory Center for Eastern Sierra Aquatic Microbial Ecology (SNARL - CESAME)
 
 
DECISION ID
162599
Region 6     
Convict Creek
 
Pollutant: Alkalinity as CaCO3
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 162599, Alkalinity as CaCO3
Region 6     
Convict Creek
 
LOE ID: 337984
 
Pollutant: Alkalinity as CaCO3
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB6 Monitoring data for Convict Creek to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Alkalinity as CaCO3.
Data Reference: Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: Water Quality Control Plan for the Lahontan Region (as amended)
 
Evaluation Guideline: The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: CON.30 (Convict Ck below Hwy 395).
Temporal Representation: The samples were collected between the dates of 2021-06-15 and 2021-10-05
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 162599, Alkalinity as CaCO3
Region 6     
Convict Creek
 
LOE ID: 337878
 
Pollutant: Alkalinity as CaCO3
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data for Convict Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Alkalinity as CaCO3.
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: Water Quality Control Plan for the Lahontan Region (as amended)
 
Evaluation Guideline: The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
168680
Region 6     
Convict Creek
 
Pollutant: Ammonia
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 168680, Ammonia
Region 6     
Convict Creek
 
LOE ID: 338120
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data for Convict Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The total ammonia water quality objective to protect aquatic life in freshwater is temperature and pH dependent and is calculated according to the equation for the four-day criterion defined in Chapter 3 of The Water Quality Control Plan for the Lahontan Region.
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: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 168680, Ammonia
Region 6     
Convict Creek
 
LOE ID: 338310
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data for Convict Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The un-ionized ammonia water quality objective to protect aquatic life in freshwater is temperature and pH dependent and is calculated according to the equation for the four-day criterion defined in Chapter 3 of The Water Quality Control Plan for the Lahontan Region.
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: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
170905
Region 6     
Convict Creek
 
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 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. Zero of two 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. Zero of two 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 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 170905, Benthic Community Effects
Region 6     
Convict Creek
 
LOE ID: 352698
 
Pollutant: Benthic-Macroinvertebrate Bioassessments
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: Water Board staff assessed data for 603CVC324 to determine beneficial use support and the results are as follows: 0 of 2 samples exceeded the water quality standard. CSCI scores were from 0.96538327384 to 0.990559834 .
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Lahontan Basin Plan)
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: Bioassessment in complex environments: designing an index for consistent meaning in different settings
 
Spatial Representation: The samples were collected at 1 monitoring site: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: Samples were collected from 2018-09-25 to 2021-06-30.
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
163790
Region 6     
Convict Creek
 
Pollutant: Chloride
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 163790, Chloride
Region 6     
Convict Creek
 
LOE ID: 342754
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data to determine beneficial use support and results are as follows:
0 of 2 samples exceeded the water quality threshold for Chloride
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Basin Plan objective for Chloride in this water body is 1.5 (mg/L), (as a Mean).
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: Convict Creek below Convict Lake (603CVC324)
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: NA
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
170622
Region 6     
Convict Creek
 
Pollutant: Mercury
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 170622, Mercury
Region 6     
Convict Creek
 
LOE ID: 337173
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB6 Monitoring data for Convict Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for Mercury .
Data Reference: Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. (Water Quality Control Plan for the Lahontan Region)
Objective/Criterion Reference: Water Quality Control Plan for the Lahontan Region (as amended)
 
Evaluation Guideline: The evaluation guideline for mercury is the probable effect concentration (PEC) of 1.06 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): CON.30 (Convict Ck below Hwy 395).
Temporal Representation: Data for this waterbody were collected over the date range 2021-05-05 to 2021-10-05
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
168971
Region 6     
Convict Creek
 
Pollutant: Nitrogen
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 168971, Nitrogen
Region 6     
Convict Creek
 
LOE ID: 343077
 
Pollutant: Total Nitrogen as N
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Nitrogen, Total
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Basin Plan objective for Nitrogen, Total in this water body is 0.3 (mg/L), (as a Mean).
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: Convict Creek below Convict Lake (603CVC324)
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2018-09-25
Environmental Conditions:
QAPP Information: NA
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
169396
Region 6     
Convict Creek
 
Pollutant: Nitrogen, Nitrate
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 169396, Nitrogen, Nitrate
Region 6     
Convict Creek
 
LOE ID: 343023
 
Pollutant: Nitrogen, Nitrate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Nitrate as N
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Basin Plan objective for Nitrate as N in this water body is 0.2 (mg/L), (as a Mean).
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: Convict Creek below Convict Lake (603CVC324)
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2018-09-25
Environmental Conditions:
QAPP Information: NA
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
163792
Region 6     
Convict Creek
 
Pollutant: Orthophosphate
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation:
 
 
Line of Evidence (LOE) for Decision ID 163792, Orthophosphate
Region 6     
Convict Creek
 
LOE ID: 343188
 
Pollutant: Orthophosphate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for OrthoPhosphate as P
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Basin Plan objective for OrthoPhosphate as P in this water body is 0.03 (mg/L), (as a Mean).
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: Convict Creek below Convict Lake (603CVC324)
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2018-09-25
Environmental Conditions:
QAPP Information: NA
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
162596
Region 6     
Convict Creek
 
Pollutant: Oxygen, Dissolved
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.

Three lines of evidence are available in the administrative record to assess this parameter: Two which assess dissolved oxygen concentration data and one which assesses dissolved oxygen percent saturation data. Zero of 7 samples are below the objective for minimum dissolved oxygen concentration. Zero of 5 samples are below the objective for minimum dissolved oxygen percent saturation.


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. Zero of 7 samples are below the objective for minimum dissolved oxygen concentration. Zero of 5 samples are below the objective for minimum dissolved oxygen percent saturation. 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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation:
 
 
Line of Evidence (LOE) for Decision ID 162596, Oxygen, Dissolved
Region 6     
Convict Creek
 
LOE ID: 339435
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB6 Monitoring data for Convict Creek to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Oxygen, Saturation.
Data Reference: Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.
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: CON.30 (Convict Ck below Hwy 395).
Temporal Representation: The samples were collected between the dates of 2021-06-15 and 2021-10-05
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 162596, Oxygen, Dissolved
Region 6     
Convict Creek
 
LOE ID: 339083
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data for Convict Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: For waters with the beneficial uses of COLD, COLD with SPWN, WARM, and WARM with SPWN, the minimum dissolved oxygen concentration shall not be less than that specified in Table 3-6. (Water Quality Control Plan, Lahontan Region)
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: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 162596, Oxygen, Dissolved
Region 6     
Convict Creek
 
LOE ID: 339271
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB6 Monitoring data for Convict Creek to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: For waters with the beneficial uses of COLD, COLD with SPWN, WARM, and WARM with SPWN, the minimum dissolved oxygen concentration shall not be less than that specified in Table 3-6. (Water Quality Control Plan, Lahontan Region)
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: CON.30 (Convict Ck below Hwy 395).
Temporal Representation: The samples were collected between the dates of 2021-06-15 and 2021-10-05
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
168651
Region 6     
Convict Creek
 
Pollutant: Specific Conductivity
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 168651, Specific Conductivity
Region 6     
Convict Creek
 
LOE ID: 340399
 
Pollutant: Specific Conductivity
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data for Convict Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for SpecificConductivity.
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL) based upon drinking water standards specified in Title 22 of the California Code of Regulations (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: Water Quality Control Plan for the Lahontan Region (as amended)
 
Evaluation Guideline: California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's 'Chemical Constituents' objective. The California Secondary MCL for specific conductivity is 900 uS/cm.
Guideline Reference: California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring
 
Spatial Representation: The samples were collected at 1 monitoring site: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 168651, Specific Conductivity
Region 6     
Convict Creek
 
LOE ID: 340517
 
Pollutant: Specific Conductivity
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB6 Monitoring data for Convict Creek to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for SpecificConductivity.
Data Reference: Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Water designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL) based upon drinking water standards specified in Title 22 of the California Code of Regulations (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: Water Quality Control Plan for the Lahontan Region (as amended)
 
Evaluation Guideline: California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's 'Chemical Constituents' objective. The California Secondary MCL for specific conductivity is 900 uS/cm.
Guideline Reference: California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring
 
Spatial Representation: The samples were collected at 1 monitoring site: CON.30 (Convict Ck below Hwy 395).
Temporal Representation: The samples were collected between the dates of 2021-06-15 and 2021-10-05
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
163791
Region 6     
Convict Creek
 
Pollutant: Sulfates
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 163791, Sulfates
Region 6     
Convict Creek
 
LOE ID: 343318
 
Pollutant: Sulfates
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Sulfate
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Basin Plan objective for Sulfate in this water body is 11 (mg/L), (as a Mean).
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: Convict Creek below Convict Lake (603CVC324)
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2018-09-25
Environmental Conditions:
QAPP Information: NA
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 163791, Sulfates
Region 6     
Convict Creek
 
LOE ID: 343324
 
Pollutant: Sulfates
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Sulfate
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Basin Plan objective for Sulfate in this water body is 11 (mg/L), (as a Mean).
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: Convict Creek below Convict Lake (603CVC324)
Temporal Representation: The samples were collected between the dates of 2021-06-30 and 2021-06-30
Environmental Conditions:
QAPP Information: NA
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
162598
Region 6     
Convict Creek
 
Pollutant: Turbidity
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: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 162598, Turbidity
Region 6     
Convict Creek
 
LOE ID: 340862
 
Pollutant: Turbidity
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data for Convict Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Turbidity.
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL) based upon drinking water standards specified in Title 22 of the California Code of Regulations. The Lahontan Basin Plan also has regionwide turbidity objective for other beneficial uses that states: Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10%.
Objective/Criterion Reference: Water Quality Control Plan for the Lahontan Region (as amended)
 
Evaluation Guideline: California Maximum Contaminant Levels (MCLs) apply to ambient surface waters under the Lahontan Basin Plan's 'Chemical Constituents' objective. The Secondary MCL for turbidity is 5 NTU. Calculation of a numeric objective for other beneficial uses requires comparison with upstream or other background data which may not be available as part of the data used for water quality assessment.
Guideline Reference: California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring
 
Spatial Representation: The samples were collected at 1 monitoring site: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
 
DECISION ID
162597
Region 6     
Convict Creek
 
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
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
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. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation:
 
 
Line of Evidence (LOE) for Decision ID 162597, pH
Region 6     
Convict Creek
 
LOE ID: 340097
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB6 Monitoring data for Convict Creek to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.
Data Reference: Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The Lahontan Basin Plan's regionwide objective for pH states: 'In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis.'
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: CON.30 (Convict Ck below Hwy 395).
Temporal Representation: The samples were collected between the dates of 2021-06-15 and 2021-10-05
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 162597, pH
Region 6     
Convict Creek
 
LOE ID: 340016
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP RWB6 Monitoring data for Convict Creek to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.
Data Reference: Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: The Lahontan Basin Plan's regionwide objective for pH states: 'In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis.'
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: CON.30 (Convict Ck below Hwy 395).
Temporal Representation: The samples were collected between the dates of 2021-06-15 and 2021-10-05
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 162597, pH
Region 6     
Convict Creek
 
LOE ID: 339859
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data for Convict Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Lahontan Basin Plan's regionwide objective for pH states: 'In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis.'
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: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP
 
Line of Evidence (LOE) for Decision ID 162597, pH
Region 6     
Convict Creek
 
LOE ID: 339546
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed USFS Management Indicator Species - Streams data for Convict Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.
Data Reference: Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Lahontan Basin Plan's regionwide objective for pH states: 'In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis.'
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: 603CVC324 (Convict Creek below Convict Lake).
Temporal Representation: The samples were collected between the dates of 2018-09-25 and 2021-06-30
Environmental Conditions:
QAPP Information: Generic SWAMP QAPrP
QAPP Information Reference(s): Generic SWAMP QAPrP