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

Supporting Information

Regional Board 9 - San Diego Region

Water Body Name:	Via Milpas
Water Body ID:	CAR9022200020190613034286
Water Body Type:	River & Stream


DECISION ID	127814	Region 9
Via Milpas

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:

Line of Evidence (LOE) for Decision ID 127814, Ammonia	Region 9
Via Milpas

LOE ID:

184983

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 Via Milpas to determine beneficial use support and results are as follows: 0 of 12 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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 127814, Ammonia	Region 9
Via Milpas

LOE ID:

184984

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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	115571	Region 9
Via Milpas

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:	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 115571, Ammonia (Unionized)	Region 9
Via Milpas

LOE ID:

185591

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 Via Milpas to determine beneficial use support and the results are as follows: 0 of the 7 samples exceeded the water quality threshold for Ammonia as N, Unionized. Although a total of 20 samples were collected, 13 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 (VMT01).

Temporal Representation:

Data for this waterbody was collected over the date range 2010-09-22 to 2012-05-15

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 115571, Ammonia (Unionized)	Region 9
Via Milpas

LOE ID:

185572

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 (VMT01).

Temporal Representation:

Data for this waterbody was collected over the date range 2010-09-22 to 2012-05-15

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	127825	Region 9
Via Milpas

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 18 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 18 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 127825, Nitrogen, Nitrite	Region 9
Via Milpas

LOE ID:

144090

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 Via Milpas to determine beneficial use support and results are as follows: 0 of 18 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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	114747	Region 9
Via Milpas

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 114747, Oxygen, Dissolved	Region 9
Via Milpas

LOE ID:

144952

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:

Water Board staff assessed Nutrient TMDL for Santa Margarita Watershed data for Via Milpas to determine beneficial use support and results are as follows: 1 of 17 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 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2017-03-09

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 114747, Oxygen, Dissolved	Region 9
Via Milpas

LOE ID:

144595

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, 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2017-03-09

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	127434	Region 9
Via Milpas

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 127434, Specific Conductivity	Region 9
Via Milpas

LOE ID:

146943

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:

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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	114748	Region 9
Via Milpas

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 114748, pH	Region 9
Via Milpas

LOE ID:

145338

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 Via Milpas to determine beneficial use support and results are as follows: 0 of 19 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2017-03-09

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 114748, pH	Region 9
Via Milpas

LOE ID:

145693

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2017-03-09

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	114746	Region 9
Via Milpas

Pollutant:	Iron
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. Four of the eight samples exceed the water quality threshold for the MUN beneficial use. Two of nine 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 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. Four of eight 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:

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 114746, Iron	Region 9
Via Milpas

LOE ID:

142858

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:

Water Board staff assessed Nutrient TMDL for Santa Margarita Watershed data for Via Milpas to determine beneficial use support and results are as follows: 2 of 9 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-04-19

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 114746, Iron	Region 9
Via Milpas

LOE ID:

142576

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 Via Milpas to determine beneficial use support and results are as follows: 4 of 8 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:

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-04-19

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 114746, Iron	Region 9
Via Milpas

LOE ID:

142716

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:

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-04-19

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	127575	Region 9
Via Milpas

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. Ten of the ten 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. Ten of the ten 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 127575, Nitrogen	Region 9
Via Milpas

LOE ID:

144184

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:

Water Board staff assessed Nutrient TMDL for Santa Margarita Watershed data for Via Milpas to determine beneficial use support and results are as follows: 10 of 10 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2011-12-09

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 127575, Nitrogen	Region 9
Via Milpas

LOE ID:

144132

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:

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2011-12-09

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	114749	Region 9
Via Milpas

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. Eleven of the 18 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. Eleven of the 18 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 114749, Phosphorus	Region 9
Via Milpas

LOE ID:

145764

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 Via Milpas to determine beneficial use support and results are as follows: 11 of 18 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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 114749, Phosphorus	Region 9
Via Milpas

LOE ID:

146023

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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	114750	Region 9
Via Milpas

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. Eight of the eight 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. Eight of eight 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 114750, Sulfates	Region 9
Via Milpas

LOE ID:

147153

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 Via Milpas to determine beneficial use support and results are as follows: 8 of 8 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-04-19

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	114751	Region 9
Via Milpas

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. Seventeen of the 18 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. Seventeen of 18 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 114751, Total Dissolved Solids	Region 9
Via Milpas

LOE ID:

147382

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 Via Milpas to determine beneficial use support and results are as follows: 17 of 18 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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 114751, Total Dissolved Solids	Region 9
Via Milpas

LOE ID:

147012

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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 114751, Total Dissolved Solids	Region 9
Via Milpas

LOE ID:

147355

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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 114751, Total Dissolved Solids	Region 9
Via Milpas

LOE ID:

147354

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2012-05-15

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	114752	Region 9
Via Milpas

Pollutant:	Turbidity
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. Three lines of evidence are available in the administrative record to assess this pollutant. Nine of the 18 samples exceed the MUN beneficial use 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. Nine of 18 samples exceed the MUN 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 114752, Turbidity	Region 9
Via Milpas

LOE ID:

147647

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 Via Milpas to determine beneficial use support and results are as follows: 9 of 18 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2017-03-09

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 114752, Turbidity	Region 9
Via Milpas

LOE ID:

147694

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:

Water Board staff assessed Nutrient TMDL for Santa Margarita Watershed data for Via Milpas to determine beneficial use support and results are as follows: 2 of 18 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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2017-03-09

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 114752, Turbidity	Region 9
Via Milpas

LOE ID:

147538

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:

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 (VMT01)

Temporal Representation:

The samples were collected between the dates of 2010-09-22 and 2017-03-09

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