Draft California 2024 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)
Water Body ID:	CAR2055001020210603031846
Water Body Type:	River & Stream


DECISION ID	144267	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito 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 144267, Alkalinity as CaCO3	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

277334

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BASMAA RMC Monitoring in WY2015 data for Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

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:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144267, Alkalinity as CaCO3	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

276990

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

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:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan


DECISION ID	150973	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito 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 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

278250

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BASMAA RMC Monitoring in WY2018 data for Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

277749

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

279551

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

277799

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

278786

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

278706

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

279923

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

279537

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

279282

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

279385

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

279411

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 150973, Ammonia	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

278531

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan


DECISION ID	151752	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito 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. Three line(s) of evidence evaluating benthic-macroinvertebrate bioassessment data is/are available in the administrative record to assess this indicator. One of three benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold. However, a minimum of two benthic-macroinvertebrate samples are needed to assess listing status. 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. One of three benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. The available information is insufficient to determine whether the waterbody/pollutant combination should 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. 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 151752, Benthic Community Effects	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

306481

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 205R03847 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the threshold. CSCI scores were from 1.197090629 to 1.197090629.

Data Reference:

California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 2.

SWAMP Data:

Non-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 (Basin Plan) San Francisco Bay Basin (Region 2)

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 (Rehn, 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.Â

Guideline Reference:

Bioassessment in complex environments: designing an index for consistent meaning in different settings

Spatial Representation:

Samples were collected from station 205R03847.

Temporal Representation:

Samples were collected from 5/7/2018 to 5/7/2018.

Environmental Conditions:

QAPP Information:

Data were collected according to BASMAA Regional Monitoring Coalition sampling protocols.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 151752, Benthic Community Effects	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

306470

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 205R02119 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.684614 to 0.684614.

Data Reference:

California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Bioassessment in complex environments: designing an index for consistent meaning in different settings

Spatial Representation:

Samples were collected from station 205R02119.

Temporal Representation:

Samples were collected from 4/29/2015 to 4/29/2015.

Environmental Conditions:

QAPP Information:

Data were collected according to BASMAA Regional Monitoring Coalition sampling protocols.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 151752, Benthic Community Effects	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

306471

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 205R03591 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the threshold. CSCI scores were from 1.055015821 to 1.055015821.

Data Reference:

California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Bioassessment in complex environments: designing an index for consistent meaning in different settings

Spatial Representation:

Samples were collected from station 205R03591.

Temporal Representation:

Samples were collected from 5/7/2018 to 5/7/2018.

Environmental Conditions:

QAPP Information:

Data were collected according to BASMAA Regional Monitoring Coalition sampling protocols.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan


DECISION ID	144262	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito 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:

Line of Evidence (LOE) for Decision ID 144262, Chloride	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

281534

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144262, Chloride	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

281885

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144262, Chloride	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

281777

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144262, Chloride	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

281592

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144262, Chloride	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

281775

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144262, Chloride	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

281917

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan


DECISION ID	144263	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

Pollutant:	Chlorine
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. Although there was a sufficient number of samples to assess total chlorine, this water body was given a use rating of Insufficient Information and a Do Not List decision. First, data were collected with field instruments that do not have the sensitivity to detect low levels of total chlorine to assess the freshwater water quality objectives of 11 ug/L and 19 ug/L. Secondly, most of the data were collected only once for a given site, and the data were not collected with the purpose of assessing chlorine levels in the water body. A more appropriate sampling to determine water quality impacts of chlorine might be conducted for future Integrated Report assessments.

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 144263, Chlorine	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

282564

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BASMAA RMC Monitoring in WY2018 data for Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144263, Chlorine	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

282669

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BASMAA RMC Monitoring in WY2018 data for Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144263, Chlorine	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

282474

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BASMAA RMC Monitoring in WY2018 data for Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144263, Chlorine	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

282563

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BASMAA RMC Monitoring in WY2018 data for Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144263, Chlorine	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

282750

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BASMAA RMC Monitoring in WY2015 data for Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144263, Chlorine	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

282783

Pollutant:

Chlorine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed BASMAA RMC Monitoring in WY2015 data for Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan


DECISION ID	144264	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito 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:	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 144264, Oxygen, Dissolved	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

285809

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144264, Oxygen, Dissolved	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

286048

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144264, Oxygen, Dissolved	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

285565

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144264, Oxygen, Dissolved	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

286026

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144264, Oxygen, Dissolved	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

286027

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144264, Oxygen, Dissolved	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

285994

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan


DECISION ID	144266	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

Pollutant:	Temperature, water
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 144266, Temperature, water	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

298809

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.

Guideline Reference:

EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA

Guideline Reference:

U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.

Guideline Reference:

Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.

Guideline Reference:

Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144266, Temperature, water	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

298879

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144266, Temperature, water	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

288496

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.

Guideline Reference:

Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C

Guideline Reference:

Inland Fishes of California

Guideline Reference:

Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144266, Temperature, water	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

288515

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Inland Fishes of California

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144266, Temperature, water	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

288489

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Inland Fishes of California

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144266, Temperature, water	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

298878

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan


DECISION ID	144265	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito 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 144265, pH	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

287096

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R02119 (Los Trancos Creek at Los Trancos Rd).

Temporal Representation:

The samples were collected between the dates of 2015-04-29 and 2015-04-29

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144265, pH	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

287199

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03847 (Los Trancos Creek at Alpine Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 144265, pH	Region 2
Los Trancos Creek (San Mateo and Santa Clara County, tributary to San Francisquito Creek)

LOE ID:

286892

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 205R03591 (Los Trancos Creek at Carmel Way).

Temporal Representation:

The samples were collected between the dates of 2018-05-07 and 2018-05-07

Environmental Conditions:

QAPP Information:

EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Creek Status Monitoring Program Quality Assurance Project Plan