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

Supporting Information

Regional Board 3 - Central Coast Region

Water Body Name:	Amesti Creek (Santa Cruz County)
Water Body ID:	CAR3051003020200327051930
Water Body Type:	River & Stream


DECISION ID	115468	Region 3
Amesti Creek (Santa Cruz County)

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:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence (LOEs) are available in the administrative record to assess this pollutant. Sample and exceedance counts for the lines of evidence with the fraction identified as "dissolved" are grouped together with those having the fraction “total”, based on the analytical method used. None of the samples exceed the water quality objective and there are an insufficient sample size to determine the applicable beneficial use support rating with the statistical power and confidence of the Listing Policy (i.e., a minimum of 26 samples is needed to determine if a beneficial use is supported and a minimum of two exceedances is needed to determine if beneficial uses are not supported using tables 3.1 and 4.1 respectively, of the Listing Policy). Therefore, the use support rating is set to 'insufficient information'. Based on the readily available data and information, there is not sufficient justification for placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the samples exceed the water quality objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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 115468, Ammonia	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

183859

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed City of Watsonville Pinto Lake Monitoring data for Amesti Creek (Santa Cruz County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Ammonia as N.

Data Reference:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Water Quality Control Plan, Central Coast Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

EPA's Lifetime Health advisory level for total ammonia is 30.0 mg/L as stated on page 8 of the 2012 edition of the drinking water standards and health advisories. This Advisory Level is defined as 'the concentration of a chemical in drinking water that is not expected to cause any adverse noncarcinogenic effects for a lifetime of exposure.'

Guideline Reference:

2018 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site (PLAMESTI)

Temporal Representation:

The samples were collected between the dates of 2016-01-05 and 2016-12-15

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 115468, Ammonia	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

183877

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed City of Watsonville Pinto Lake Monitoring data for Amesti Creek (Santa Cruz County) 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:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

Guideline Reference:

2018 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site (PLAMESTI)

Temporal Representation:

The samples were collected between the dates of 2016-01-19 and 2017-01-03

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 115468, Ammonia	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

183861

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed City of Watsonville Pinto Lake Monitoring data for Amesti Creek (Santa Cruz County) 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:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

Guideline Reference:

2018 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site (PLAmestiUp)

Temporal Representation:

The samples were collected between the dates of 2017-01-03 and 2017-01-03

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 115468, Ammonia	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

183860

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed City of Watsonville Pinto Lake Monitoring data for Amesti Creek (Santa Cruz County) 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:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

Guideline Reference:

2018 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site (PLAmestiUp)

Temporal Representation:

The samples were collected between the dates of 2016-12-08 and 2016-12-15

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan


DECISION ID	115467	Region 3
Amesti Creek (Santa Cruz County)

Pollutant:	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:	This pollutant is being considered for placement on the CWA section 303(d) List under sections 3.1 and 3.11 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Under section 3.11, additional lines of evidence are necessary to support a listing decision. Six lines of evidence are available in the administrative record to assess this pollutant. Zero of the eight samples exceed the water quality objective for the Municipal and Domestic Supply beneficial use. Although five of the eight samples do exceed the Central Coast Region’s evaluation guideline for maximum nitrate concentration and the protection of aquatic life uses from bio-stimulatory or eutrophic effects (R3 NNE Technical Report, 2010), Central Coast Region requires supporting evidence indicating high risk for, or occurrence of, eutrophication in accordance with section 3.11 of the Listing Policy. There is no dissolved oxygen or other data available to use as supporting evidence of a bio-stimulatory or eutrophic effects and therefore the beneficial use rating is set to insufficient information. 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. 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 and there is no supporting evidence to confirm an impairment to the aquatic life uses. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the eight samples exceed the water quality objective for the Municipal and Domestic Supply beneficial use. This does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. Although, there are exceedances of the evaluation guideline for aquatic life uses, additional supporting evidence is necessary to support a decision based on these exceedances in accordance with section 3.11 of the Listing Policy. No additional data are available to support a conclusion that nitrate causes or contributes to bio-stimulatory responses in this waterbody. 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 115467, Nitrate	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

172238

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 City of Watsonville Pinto Lake Monitoring data for Amesti Creek (Santa Cruz County) to determine beneficial use support and results are as follows: 5 of 5 samples exceeded the water quality threshold for Nitrate as N.

Data Reference:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect beneficial uses (Water Quality Control Plan, Central Coast Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

Technical approach to develop nutrient numeric endpoints for California, Tetra Tech, June 2006. The Central Coast Region numeric target for maximum nitrate concentration is based on the Tetra Tech NNE (Nutrient Numeric Endpoint) Model and CCAMP data for 193 sites, monitored monthly for at least 1 year between January 1998 and December 2006. The model numeric target for aquatic life habitats in the Central Coast Region is 1.0 mg/L Nitrate as N.

Guideline Reference:

Central Coast RegionTechnical Paper: Interpreting Narrative Objectives for Biostimulatory Substances for California Central Coast Waters. This method uses the Technical Approach for Developing California Nutrient Numeric Endpoints.

Spatial Representation:

The samples were collected at 1 monitoring site (PLAMESTI)

Temporal Representation:

The samples were collected between the dates of 2016-01-05 and 2017-01-03

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 115467, Nitrate	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

172826

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (PLAmestiUp)

Temporal Representation:

The samples were collected between the dates of 2016-12-08 and 2017-01-03

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 115467, Nitrate	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

172112

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed City of Watsonville Pinto Lake Monitoring data for Amesti Creek (Santa Cruz County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Nitrate as N.

Data Reference:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

All inland surface waters, enclosed bays, and estuaries shall not contain concentrations of inorganic chemicals in excess of the maximum contaminant levels for primary drinking water standards specified in California Code of Regulations, Title 22, Division 4, Chapter 15, Sections 64431 and 64433.2.

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

The California Maximum Contaminant Level for nitrate (as N) 10.0 mg/L (California Code of Regulations, Title 22).

Guideline Reference:

California MCLs - Title 17 and Title 22 documents for 2019 - California Regulations Related to Drinking Water

Spatial Representation:

The samples were collected at 1 monitoring site (PLAMESTI)

Temporal Representation:

The samples were collected between the dates of 2016-01-05 and 2017-01-03

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 115467, Nitrate	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

172260

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

The California Maximum Contaminant Level for nitrate (as N) 10.0 mg/L (California Code of Regulations, Title 22).

Guideline Reference:

California MCLs - Title 17 and Title 22 documents for 2019 - California Regulations Related to Drinking Water

Spatial Representation:

The samples were collected at 1 monitoring site (PLAmestiUp)

Temporal Representation:

The samples were collected between the dates of 2016-12-08 and 2017-01-03

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 115467, Nitrate	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

172092

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (PLAMESTI)

Temporal Representation:

The samples were collected between the dates of 2016-01-05 and 2017-01-03

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 115467, Nitrate	Region 3
Amesti Creek (Santa Cruz County)

LOE ID:

172388

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Water data for the 2020/2022 integrated report in Region 3.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Central Coastal Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (PLAmestiUp)

Temporal Representation:

The samples were collected between the dates of 2016-12-08 and 2017-01-03

Environmental Conditions:

QAPP Information:

City of Watsonville. 2015. Pinto Lake Restoration Project Quality Assurance Program Plan.

QAPP Information Reference(s):

Pinto Lake Restoration Project Quality Assurance Program Plan