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

Supporting Information

Regional Board 9 - San Diego Region

Water Body Name:	Willow Glen
Water Body ID:	CAR9022200020190613036429
Water Body Type:	River & Stream


DECISION ID	127785	Region 9
Willow Glen

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. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the 46 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List 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. Zero of the 46 samples exceed the water quality threshold, 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 because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 127785, Ammonia	Region 9
Willow Glen

LOE ID:

185293

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 0 of 46 samples exceeded the water quality threshold for Ammonia as N.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

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 (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 127785, Ammonia	Region 9
Willow Glen

LOE ID:

185102

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, Water data for the 2020/2022 integrated report in Region 9.

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 (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	115572	Region 9
Willow Glen

Pollutant:	Ammonia (Unionized)
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. Two lines of evidence are available in the administrative record to assess this pollutant. One of the 23 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List 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. One of the 23 samples exceed the water quality threshold 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 because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 115572, Ammonia (Unionized)	Region 9
Willow Glen

LOE ID:

185586

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:

Water Board staff assessed Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and the results are as follows: 1 of the 23 samples exceeded the water quality threshold for Ammonia as N, Unionized. Although a total of 72 samples were collected, 49 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The discharge of wastes shall not cause concentrations of un-ionized ammonia (NH3) to exceed 0.025 mg/l (as N) in inland surface waters, enclosed bays and estuaries and coastal lagoons (Water Quality Control Plan, San Diego Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01).

Temporal Representation:

Data for this waterbody was collected over the date range 2010-09-22 to 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 115572, Ammonia (Unionized)	Region 9
Willow Glen

LOE ID:

185364

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01).

Temporal Representation:

Data for this waterbody was collected over the date range 2010-09-22 to 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	114753	Region 9
Willow Glen

Pollutant:	Iron
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. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the 33 samples exceed the water quality threshold for the MUN beneficial use. Zero of 35 samples exceed the water quality threshold for the WARM/COLD beneficial use. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List 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. Zero of 33 samples exceeded the water quality threshold, 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 because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 114753, Iron	Region 9
Willow Glen

LOE ID:

142766

Pollutant:

Iron

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and the results are as follows: 0 of the 33 samples exceeded the water quality threshold for Iron. Although a total of 34 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Secondary California Maximum Contaminant Level for Iron is 0.3 mg/L (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01).

Temporal Representation:

Data for this waterbody was collected over the date range 2010-09-22 to 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114753, Iron	Region 9
Willow Glen

LOE ID:

142769

Pollutant:

Iron

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 0 of 35 samples exceeded the water quality threshold for Iron.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

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 for the San Diego Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentrations are intended protect aquatic organisms from chronic exposures (expressed as 4-day average concentration) in freshwater. The evaluation guideline for iron is 1,000 ug/L to protect warm freshwater habitat.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114753, Iron	Region 9
Willow Glen

LOE ID:

142765

Pollutant:

Iron

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	127794	Region 9
Willow Glen

Pollutant:	Nitrogen, Nitrite
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. One lines of evidence are available in the administrative record to assess this pollutant. Zero of the 70 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List 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. Zero of the 70 samples exceed the water quality threshold 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 because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 127794, Nitrogen, Nitrite	Region 9
Willow Glen

LOE ID:

144033

Pollutant:

Nitrogen, Nitrite

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 0 of 70 samples exceeded the water quality threshold for Nitrite as N.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for nitrite (as N) is 1.0 mg/L (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

Title 22. Division 4. Chapter 15. Sections 64400 et seq. California Code of Regulations

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	114754	Region 9
Willow Glen

Pollutant:	Oxygen, Dissolved
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2, a single line of evidence is necessary to assess listing status. Two line(s) of evidence are available in the administrative record to assess this pollutant. Zero of the 90 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 90 samples exceeded the water quality threshold, and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 114754, Oxygen, Dissolved	Region 9
Willow Glen

LOE ID:

144888

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:

Water Board staff assessed Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 0 of 90 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen levels shall not be less than 6.0 mg/l in inland surface waters with the COLD beneficial use designated (Water Quality Control Plan, San Diego Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114754, Oxygen, Dissolved	Region 9
Willow Glen

LOE ID:

144782

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen levels shall not be less than 5.0 mg/l in inland surface waters with the WARM beneficial use designated (Water Quality Control Plan, San Diego Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	127446	Region 9
Willow Glen

Pollutant:	Specific Conductivity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. Zero of the 59 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 59 samples exceeded the threshold and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 127446, Specific Conductivity	Region 9
Willow Glen

LOE ID:

146869

Pollutant:

Specific Conductivity

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 0 of 59 samples exceeded the water quality threshold for SpecificConductivity.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the maximum contaminant levels specified in Table 64449-A of section 64449 of Title 22 of the California Code of Regulations (Secondary Maximum Contaminant Levels, Consumer Acceptance Limits) which is incorporated by reference into this plan. (Water Quality Control Plan, San Diego Basin). The California Secondary MCL for specific conductance is 900 uS/cm (Title 22 California Code of Regulations).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2015-09-03

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	114759	Region 9
Willow Glen

Pollutant:	Turbidity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Nine of the 92 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Nine of the 92 samples exceed the water quality threshold and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 114759, Turbidity	Region 9
Willow Glen

LOE ID:

147907

Pollutant:

Turbidity

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 9 of 92 samples exceeded the water quality threshold for Turbidity.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Secondary California Maximum Contaminant Level for Turbidity is 5 NTU (Title 22 of the California Code of Regulations).

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114759, Turbidity	Region 9
Willow Glen

LOE ID:

147633

Pollutant:

Turbidity

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 0 of 92 samples exceeded the water quality threshold for Turbidity.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Turbidity water quality threshold in this HSA is 20 NTU, and this level is not to be exceeded more than 10% of the time during any one year period (Basin Plan, Table 3-2).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114759, Turbidity	Region 9
Willow Glen

LOE ID:

147750

Pollutant:

Turbidity

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Turbidity water quality threshold in this HSA is 20 NTU, and this level is not to be exceeded more than 10% of the time during any one year period (Basin Plan, Table 3-2).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	114755	Region 9
Willow Glen

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:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2, a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. One of the 95 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of 95 samples exceeded the water quality threshold, and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 114755, pH	Region 9
Willow Glen

LOE ID:

145077

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:

Water Board staff assessed Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 1 of 95 samples exceeded the water quality threshold for pH.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

In inland surface waters the pH shall not be depressed below 6.5 nor raised above 8.5.

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114755, pH	Region 9
Willow Glen

LOE ID:

145213

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

In inland surface waters the pH shall not be depressed below 6.5 nor raised above 8.5.

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	127528	Region 9
Willow Glen

Pollutant:	Nitrogen
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	A Source Unknown
Expected TMDL Completion Date:	2033
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. Two lines of evidence are available in the administrative record to assess this pollutant. Thirty-six of the 37 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Thirty-six of the 37 samples exceed the water quality threshold, and this exceeds 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 be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 127528, Nitrogen	Region 9
Willow Glen

LOE ID:

144095

Pollutant:

Total Nitrogen as N

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 36 of 37 samples exceeded the water quality threshold for Nitrogen, Total.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Concentrations of nitrogen and phosphorus, by themselves or in combination with other nutrients, shall be maintained at levels below those which stimulate algae and emergent plant growth. A desired goal in order to prevent plant nuisance in streams and other flowing waters appears to be 0.1 mg/L total P. Analogous threshold values have not been set for nitrogen compounds; however, natural ratios of nitrogen to phosphorus are to be determined by surveillance and monitoring and upheld. If data are lacking, a ratio of N:P = 10:1, on a weight to weight basis shall be used (Water Quality Control Plan, San Diego Basin).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-11-04 and 2015-09-03

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 127528, Nitrogen	Region 9
Willow Glen

LOE ID:

143863

Pollutant:

Total Nitrogen as N

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-11-04 and 2015-09-03

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	114756	Region 9
Willow Glen

Pollutant:	Phosphorus
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	A Source Unknown
Expected TMDL Completion Date:	2033
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. Two lines of evidence are available in the administrative record to assess this pollutant. Forty of the 71 samples exceed the threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Forty of the 71 samples exceed the threshold, and this exceeds 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 be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 114756, Phosphorus	Region 9
Willow Glen

LOE ID:

145898

Pollutant:

Phosphorus

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 40 of 71 samples exceeded the water quality threshold for Phosphorus as P.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114756, Phosphorus	Region 9
Willow Glen

LOE ID:

145848

Pollutant:

Phosphorus

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	114757	Region 9
Willow Glen

Pollutant:	Sulfates
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	A Source Unknown
Expected TMDL Completion Date:	2033
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Thirty-five of the 35 samples exceed the threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Thirty-five of 35 samples exceed the threshold, and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 114757, Sulfates	Region 9
Willow Glen

LOE ID:

146753

Pollutant:

Sulfates

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 Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 35 of 35 samples exceeded the water quality threshold for Sulfate.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Sulfate water quality threshold in this HSA is 250 mg/L, and this concentration is not to be exceeded more than 10% of the time during any one year period (Basin Plan, Table 3-2).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring


DECISION ID	114758	Region 9
Willow Glen

Pollutant:	Total Dissolved Solids
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	A Source Unknown
Expected TMDL Completion Date:	2033
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Seventy-one of the 71 samples exceed the water quality threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Seventy-one of 71 samples exceed the Basin Plan objective and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 114758, Total Dissolved Solids	Region 9
Willow Glen

LOE ID:

147189

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Nutrient TMDL for Santa Margarita Watershed data for Willow Glen to determine beneficial use support and results are as follows: 71 of 71 samples exceeded the water quality threshold for Total Dissolved Solids.

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Dissolved Solids water quality threshold in this HSA is 500 mg/L, and this concentration is not to be exceeded more than 10% of the time during any one year period (Basin Plan, Table 3-2).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114758, Total Dissolved Solids	Region 9
Willow Glen

LOE ID:

147229

Pollutant:

Total Dissolved Solids

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Dissolved Solids water quality threshold in this HSA is 500 mg/L, and this concentration is not to be exceeded more than 10% of the time during any one year period (Basin Plan, Table 3-2).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114758, Total Dissolved Solids	Region 9
Willow Glen

LOE ID:

147188

Pollutant:

Total Dissolved Solids

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:

Data Reference:

Field, Habitat, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Dissolved Solids water quality threshold in this HSA is 500 mg/L, and this concentration is not to be exceeded more than 10% of the time during any one year period (Basin Plan, Table 3-2).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring

Line of Evidence (LOE) for Decision ID 114758, Total Dissolved Solids	Region 9
Willow Glen

LOE ID:

147328

Pollutant:

Total Dissolved Solids

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, Water data for the 2020/2022 integrated report in Region 9.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Dissolved Solids water quality threshold in this HSA is 500 mg/L, and this concentration is not to be exceeded more than 10% of the time during any one year period (Basin Plan, Table 3-2).

Objective/Criterion Reference:

Water Quality Control Plan for the San Diego Basin

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (WGT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2018-09-13

Environmental Conditions:

QAPP Information:

County of San Diego. 2016. Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring.

QAPP Information Reference(s):

Quality Assurance Project Plan for Nutrient Source Reduction Program in the Rainbow Creek Watershed Water Quality Monitoring