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

Supporting Information

Regional Board 8 - Santa Ana Region

Water Body Name:	Mill Creek (Prado Area)
Water Body ID:	CAR8012100019990211144540
Water Body Type:	River & Stream

DECISION ID	149157	Region 8
Mill Creek (Prado Area)

Pollutant:	Indicator Bacteria
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	Dairies
TMDL Name:	Middle Santa Ana River Watershed Bacterial Indicator TMDLs
TMDL Project Code:	90
Date TMDL Approved by USEPA:	05/16/2007
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under sections 4.2 and 4.3 of the Listing Policy. Under these sections a single line of evidence is necessary to assess listing status. The State Water Board’s Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California (the “ISWEBE Plan”) contains two bacteria water quality objectives applicable to the REC-1 beneficial use, which were adopted on August 7, 2018. Because the salinity level of this waterbody is equal to or less than 1 part per thousand 95 percent or more of the time, the E. coli bacteria objective applies. Therefore, this waterbody is being considered for removal from the CWA section 303(d) List under section 4.3 of the Listing Policy using the E. coli objective. Four (4) lines of evidence of E. coli data are available in the administrative record to assess this pollutant. Sixty-one (61) of 62 samples exceed the E.coli Geomean objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Sixty-one (61) of 62 samples exceed the E.coli Geomean objective and this does exceed the allowable frequency listed in Table 4.2 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. In accordance with section 6.1.5.3 of the Listing Policy, data should be representative of the critical timing that the pollutant is expected to impact the waterbody. Indicator bacteria (total coliform, fecal coliform, E. coli, enterococci) populations may fluctuate substantially on a daily, seasonal, or yearly basis. Lacking constant inputs, they do not persist in the environment for a long period and effects are of relatively short duration. As a result, the historic levels of indicator bacteria in the waterbody may be a poor indicator of current risks to human health, particularly when more recent data are available to sufficiently assess the water quality standard. Unrepresentative data may result in incorrectly placing or not placing a water body segment on the list, which could result in the unnecessary expenditure of public resources or failure to address a human health risk. The one (1) historic line of evidence (LOE ID 2992) was evaluated pursuant to these considerations and was not used to assess water quality standards attainment because it does not meet the temporal representation requirements of section 6.1.5.3 of the Listing Policy. From 2010 Listing Cycle: Regional Board Conclusion: This pollutant is being considered for listing under section 2.2 of the Listing Policy. Under this section of the Policy, a minimum of one line of evidence is needed to assess listing status. The Prado Area Streams Pathogen TMDL was approved by the RWQCB in 2007 and subsequently approved by USEPA on 5/16/07. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list. State Board Review and Conclusion: This Santa Ana Regional Board staff recommended to continue listing this previously listed water body for Pathogens in the centralized database for the assessment. However, the centralized database was not used to generate the final Staff Report for Region 8 and this decision did not get included for Regional Water Board approval. Based on the review of the data and information in the centralized database, State Water Board staff recommends to continue to List this water body-pollutant combination.
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.
State Board Review of Regional Board Conclusion and Recommendation:	From 2010 Listing Cycle: Regional Board Conclusion: This pollutant is being considered for listing under section 2.2 of the Listing Policy. Under this section of the Policy, a minimum of one line of evidence is needed to assess listing status. The Prado Area Streams Pathogen TMDL was approved by the RWQCB in 2007 and subsequently approved by USEPA on 5/16/07. Based on the readily available information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list. State Board Review and Conclusion: This Santa Ana Regional Board staff recommended to continue listing this previously listed water body for Pathogens in the centralized database for the assessment. However, the centralized database was not used to generate the final Staff Report for Region 8 and this decision did not get included for Regional Water Board approval. Based on the review of the data and information in the centralized database, State Water Board staff recommends to continue to List this water body-pollutant combination.
State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 149157, Indicator Bacteria Region 8      Mill Creek (Prado Area)
LOE ID:	2992
Pollutant:	Pathogens
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Not Recorded
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	0
Number of Exceedances:	0
Data and Information Type:	Not Specified
Data Used to Assess Water Quality:	Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference:	Placeholder reference 2006 303(d)
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:
Objective/Criterion Reference:
Evaluation Guideline:
Guideline Reference:
Spatial Representation:
Temporal Representation:
Environmental Conditions:
QAPP Information:	QA Info Missing
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 149157, Indicator Bacteria Region 8      Mill Creek (Prado Area)
LOE ID:	301007
Pollutant:	Escherichia coli (E. coli)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	STV
Beneficial Use:	Water Contact Recreation
Number of Samples:	29
Number of Exceedances:	23
Data and Information Type:	PATHOGEN MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Santa Ana River Regional Monitoring Program data for Mill Creek (Prado Area) to determine beneficial use support and the results are as follows: 23 of the 29 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference:	Field, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference:	Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site(s), station(s): WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the days of 2016-03-06 and 2020-09-22 .
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program
Line of Evidence (LOE) for Decision ID 149157, Indicator Bacteria Region 8      Mill Creek (Prado Area)
LOE ID:	300949
Pollutant:	Escherichia coli (E. coli)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	GeoMean
Beneficial Use:	Water Contact Recreation
Number of Samples:	2
Number of Exceedances:	2
Data and Information Type:	PATHOGEN MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Middle Santa Ana River TMDL Monitoring Project data for Mill Creek (Prado Area) to determine beneficial use support and the results are as follows: 2 of the 2 samples exceeded the geomean water quality threshold for E. coli. This is a six week rolling geomean that is calculated weekly.
Data Reference:	Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The bacteria water quality objective to protect the REC-1 beneficial use for waters where the salinity is equal to or less than 1 part per thousand 95 percent or more of the time applies a rolling six-week geometric mean of E. coli, not to exceed 100 cfu/100 mL (ISWEBE 2018).
Objective/Criterion Reference:	Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site(s), station(s): WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the days of 2019-07-30 and 2019-09-03 .
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program
Line of Evidence (LOE) for Decision ID 149157, Indicator Bacteria Region 8      Mill Creek (Prado Area)
LOE ID:	301012
Pollutant:	Escherichia coli (E. coli)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	GeoMean
Beneficial Use:	Water Contact Recreation
Number of Samples:	60
Number of Exceedances:	59
Data and Information Type:	PATHOGEN MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Santa Ana River Regional Monitoring Program data for Mill Creek (Prado Area) to determine beneficial use support and the results are as follows: 59 of the 60 samples exceeded the geomean water quality threshold for E. coli. This is a six week rolling geomean that is calculated weekly.
Data Reference:	Field, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The bacteria water quality objective to protect the REC-1 beneficial use for waters where the salinity is equal to or less than 1 part per thousand 95 percent or more of the time applies a rolling six-week geometric mean of E. coli, not to exceed 100 cfu/100 mL (ISWEBE 2018).
Objective/Criterion Reference:	Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site(s), station(s): WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the days of 2016-03-06 and 2020-09-22 .
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program
Line of Evidence (LOE) for Decision ID 149157, Indicator Bacteria Region 8      Mill Creek (Prado Area)
LOE ID:	300888
Pollutant:	Escherichia coli (E. coli)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	STV
Beneficial Use:	Water Contact Recreation
Number of Samples:	3
Number of Exceedances:	2
Data and Information Type:	PATHOGEN MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Middle Santa Ana River TMDL Monitoring Project data for Mill Creek (Prado Area) to determine beneficial use support and the results are as follows: 2 of the 3 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference:	Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference:	Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site(s), station(s): WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the days of 2019-07-30 and 2019-09-03 .
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program

DECISION ID	132279	Region 8
Mill Creek (Prado Area)

Pollutant:	Alachlor
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132279, Alachlor Region 8      Mill Creek (Prado Area)
LOE ID:	234636
Pollutant:	Alachlor
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection Instantaneous Max: alachlor 76 ppb.
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132816	Region 8
Mill Creek (Prado Area)

Pollutant:	Alkalinity as CaCO3
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 132816, Alkalinity as CaCO3 Region 8      Mill Creek (Prado Area)
LOE ID:	235023
Pollutant:	Alkalinity as CaCO3
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	2
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed SWAMP RWB8 Monitoring data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Alkalinity as CaCO3.
Data Reference:	Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	SWAMP
Water Quality Objective/Criterion:	The concentrations of toxic pollutants in the water column, sediments or biota shall not adversely affect beneficial uses (Water Quality Control Plan for the Santa Ana River Basin).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:	The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).
Guideline Reference:	National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
Spatial Representation:	The samples were collected at 1 monitoring site: 801MIC042 (Mill Creek Random Olsen Site 042).
Temporal Representation:	The samples were collected between the dates of 2012-06-19 and 2014-06-09
Environmental Conditions:
QAPP Information:	SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s):	This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

DECISION ID	132280	Region 8
Mill Creek (Prado Area)

Pollutant:	Aluminum
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132280, Aluminum Region 8      Mill Creek (Prado Area)
LOE ID:	234698
Pollutant:	Aluminum
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the guideline.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria for Aquatic life protection: aluminum 87 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was collected at the Mill Creek at Chino sampling station.
Temporal Representation:	The sample was collected on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	150593	Region 8
Mill Creek (Prado Area)

Pollutant:	Ammonia
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 150593, Ammonia Region 8      Mill Creek (Prado Area)
LOE ID:	240217
Pollutant:	Ammonia (Unionized)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	2
Number of Exceedances:	1
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed SWAMP RWB8 Monitoring data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 1 of 2 samples exceeded the water quality standard for Ammonia as N, Unionized.
Data Reference:	Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	SWAMP
Water Quality Objective/Criterion:	Site-Specific Objective: To prevent chronic toxicity to aquatic life in the Santa Ana River, Reaches 2, 3, and 4, Chino Creek, Mill Creek (Prado Area), Temescal Creek and San Timoteo Creek, discharges to these waterbodies shall not cause the concentration of un-ionized ammonia (as nitrogen) to exceed 0.098 mg/L (NH3-N) as a 4-day average.
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site (801MIC042)
Temporal Representation:	The samples were collected between the dates of 2012-06-19 and 2014-06-09
Environmental Conditions:
QAPP Information:	SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s):	This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

DECISION ID	132258	Region 8
Mill Creek (Prado Area)

Pollutant:	Atrazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132258, Atrazine Region 8      Mill Creek (Prado Area)
LOE ID:	234637
Pollutant:	Atrazine
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection Instantaneous Max: atrazine 1 ppb.
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132268	Region 8
Mill Creek (Prado Area)

Pollutant:	Azinphos-methyl (Guthion)
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 132268, Azinphos-methyl (Guthion) Region 8      Mill Creek (Prado Area)
LOE ID:	234638
Pollutant:	Azinphos-methyl (Guthion)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection Instantaneous Max: azinphos methyl 0.01 ppb.
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	154026	Region 8
Mill Creek (Prado Area)

Pollutant:	Benthic Community Effects
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Benthic Community Effects are being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, additional lines of evidence (LOEs) associating the Benthic Community Effects decision with a water or sediment concentration of pollutants other than benthic-macroinvertebrate bioassessment or habitat assessment LOEs are necessary to place a water body on the 303(d) List for Benthic Community Effects. One line(s) of evidence evaluating benthic-macroinvertebrate bioassessment data is/are available in the administrative record to assess this indicator. One of one benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold. However, a minimum of two benthic-macroinvertebrate samples are needed to assess listing status. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing Benthic Community Effects in this waterbody segment on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of one benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. The available information is insufficient to determine whether the waterbody/pollutant combination should be placed on the 303(d) List of impaired waters at this time. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 154026, Benthic Community Effects Region 8      Mill Creek (Prado Area)
LOE ID:	314249
Pollutant:	Benthic-Macroinvertebrate Bioassessments
LOE Subgroup:	Population/Community Degradation
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	1
Data and Information Type:	Benthic macroinvertebrate surveys
Data Used to Assess Water Quality:	Water Board staff assessed data for 801M16908 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.77663304 to 0.77663304.
Data Reference:	California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 8.
SWAMP Data:	SWAMP
Water Quality Objective/Criterion:	Inland surface water communities and populations, including vertebrate, invertebrate, and plant species, shall not be degraded as a result of the discharge of waste. Degradation is damage to an aquatic community or population with the result that balanced community no longer exists. The concentrations of toxic pollutants in the water column, sediments or biota shall not adversely affect beneficial uses.
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:	The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rehn, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use.
Guideline Reference:	Bioassessment in complex environments: designing an index for consistent meaning in different settings
Spatial Representation:	Samples were collected from station 801M16908.
Temporal Representation:	Samples were collected from 5/24/2016 to 5/24/2016.
Environmental Conditions:
QAPP Information:	Data collected following SWAMP QA protocols.
QAPP Information Reference(s):	This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

DECISION ID	132259	Region 8
Mill Creek (Prado Area)

Pollutant:	Cadmium
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 132259, Cadmium Region 8      Mill Creek (Prado Area)
LOE ID:	234680
Pollutant:	Cadmium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Aquatic Life Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the standard.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	The California Toxics Rule cadmium criteria is hardness dependent and ranged as follows: cadium 2.95 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was taken in Mill Creek near Chino.
Temporal Representation:	The sample was taken on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data's quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132260	Region 8
Mill Creek (Prado Area)

Pollutant:	Carbaryl
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 132260, Carbaryl Region 8      Mill Creek (Prado Area)
LOE ID:	234639
Pollutant:	Carbaryl
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection Instantaneous Max: carbaryl 0.02 ppb
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132261	Region 8
Mill Creek (Prado Area)

Pollutant:	Carbofuran
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132261, Carbofuran Region 8      Mill Creek (Prado Area)
LOE ID:	234655
Pollutant:	Carbofuran
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection Instantaneous Max: carbofuran 0.5 ppb.
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132262	Region 8
Mill Creek (Prado Area)

Pollutant:	Chlorpyrifos
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 132262, Chlorpyrifos Region 8      Mill Creek (Prado Area)
LOE ID:	234656
Pollutant:	Chlorpyrifos
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	California Department of Fish and Game: chlropyrifos 0.014 ppb.
Guideline Reference:	Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132263	Region 8
Mill Creek (Prado Area)

Pollutant:	Chromium, hexavalent
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 132263, Chromium, hexavalent Region 8      Mill Creek (Prado Area)
LOE ID:	234699
Pollutant:	Chromium, hexavalent
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the guideline.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	CTR Fresh Water Aquatic Life Protection 4 day average continuous concentration: chromium VI 11 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was collected at the Mill Creek at Chino sampling station.
Temporal Representation:	The sample was collected on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132264	Region 8
Mill Creek (Prado Area)

Pollutant:	Copper
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 132264, Copper Region 8      Mill Creek (Prado Area)
LOE ID:	234681
Pollutant:	Copper
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Aquatic Life Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the standard.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	The California Toxics Rule cadmium criteria is hardness dependent and ranged as follows: copper 11.37 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was taken in Mill Creek near Chino.
Temporal Representation:	The sample was taken on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data's quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	149249	Region 8
Mill Creek (Prado Area)

Pollutant:	DDE (Dichlorodiphenyldichloroethylene)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 149249, DDE (Dichlorodiphenyldichloroethylene) Region 8      Mill Creek (Prado Area)
LOE ID:	234657
Pollutant:	DDE (Dichlorodiphenyldichloroethylene)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection continuous concentration 4-day average: DDE 0.001 ppb.
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132265	Region 8
Mill Creek (Prado Area)

Pollutant:	Diazinon
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 132265, Diazinon Region 8      Mill Creek (Prado Area)
LOE ID:	234658
Pollutant:	Diazinon
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	California Department of Fish and Game: diazinon 0.08 ppb.
Guideline Reference:	Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132266	Region 8
Mill Creek (Prado Area)

Pollutant:	Dieldrin
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 132266, Dieldrin Region 8      Mill Creek (Prado Area)
LOE ID:	234659
Pollutant:	Dieldrin
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	CTR Freshwater aquatic life protection continuous concentration 4-day average: dieldrin 0.056 ppb
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132267	Region 8
Mill Creek (Prado Area)

Pollutant:	Disulfoton
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132267, Disulfoton Region 8      Mill Creek (Prado Area)
LOE ID:	234660
Pollutant:	Disulfoton
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection Instantaneous Max: disulfoton 0.05 ppb.
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132269	Region 8
Mill Creek (Prado Area)

Pollutant:	Lead
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 132269, Lead Region 8      Mill Creek (Prado Area)
LOE ID:	234682
Pollutant:	Lead
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Aquatic Life Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the standard.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	The California Toxics Rule cadmium criteria is hardness dependent and ranged as follows: lead 4.27 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was taken in Mill Creek near Chino.
Temporal Representation:	The sample was taken on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data's quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132270	Region 8
Mill Creek (Prado Area)

Pollutant:	Malathion
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 132270, Malathion Region 8      Mill Creek (Prado Area)
LOE ID:	234661
Pollutant:	Malathion
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection Instantaneous Max: malathion 0.01 ppb.
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	149100	Region 8
Mill Creek (Prado Area)

Pollutant:	Mercury
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 149100, Mercury Region 8      Mill Creek (Prado Area)
LOE ID:	234700
Pollutant:	Mercury
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the guideline.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria for Aquatic life protection: mercury 0.77 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was collected at the Mill Creek at Chino sampling station.
Temporal Representation:	The sample was collected on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132271	Region 8
Mill Creek (Prado Area)

Pollutant:	Methyl Parathion
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 132271, Methyl Parathion Region 8      Mill Creek (Prado Area)
LOE ID:	234676
Pollutant:	Methyl Parathion
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	California Department of Fish and Game: parathion 0.08 ppb.
Guideline Reference:	Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132272	Region 8
Mill Creek (Prado Area)

Pollutant:	Molinate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132272, Molinate Region 8      Mill Creek (Prado Area)
LOE ID:	234677
Pollutant:	Molinate
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	California Dept of Fish and Game: molinate 13 ppb.
Guideline Reference:	Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132273	Region 8
Mill Creek (Prado Area)

Pollutant:	Nickel
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 132273, Nickel Region 8      Mill Creek (Prado Area)
LOE ID:	234695
Pollutant:	Nickel
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Aquatic Life Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the standard.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	The California Toxics Rule cadmium criteria is hardness dependent and ranged as follows: nickel 63.43 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was taken in Mill Creek near Chino.
Temporal Representation:	The sample was taken on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data's quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132812	Region 8
Mill Creek (Prado Area)

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. Four lines of evidence are available in the administrative record to assess this pollutant. Two of the 123 samples exceed the WARM dissolved oxygen objective. 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. Two of 123 samples exceeded the WARM dissolved oxygen objective 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 132812, Oxygen, Dissolved Region 8      Mill Creek (Prado Area)
LOE ID:	236989
Pollutant:	Oxygen, Dissolved
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Not Recorded
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	58
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Santa Ana River Regional Monitoring Program data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 0 of 58 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference:	Field, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The dissolved oxygen content of surface waters shall not be depressed below 5 mg/L for waters designated WARM as a result of controllable water quality factors (Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the dates of 2018-05-09 and 2020-03-16
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program
Line of Evidence (LOE) for Decision ID 132812, Oxygen, Dissolved Region 8      Mill Creek (Prado Area)
LOE ID:	237112
Pollutant:	Oxygen, Dissolved
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Not Recorded
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	6
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Middle Santa Ana River TMDL Monitoring Project data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference:	Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The dissolved oxygen content of surface waters shall not be depressed below 5 mg/L for waters designated WARM as a result of controllable water quality factors (Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the dates of 2019-07-30 and 2019-09-03
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program
Line of Evidence (LOE) for Decision ID 132812, Oxygen, Dissolved Region 8      Mill Creek (Prado Area)
LOE ID:	236836
Pollutant:	Oxygen, Dissolved
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	2
Number of Exceedances:	1
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed SWAMP RWB8 Monitoring data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 1 of 2 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference:	Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	SWAMP
Water Quality Objective/Criterion:	The dissolved oxygen content of surface waters shall not be depressed below 5 mg/L for waters designated WARM as a result of controllable water quality factors (Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: 801MIC042 (Mill Creek Random Olsen Site 042).
Temporal Representation:	The samples were collected between the dates of 2012-06-19 and 2014-06-09
Environmental Conditions:
QAPP Information:	SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s):	This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
Line of Evidence (LOE) for Decision ID 132812, Oxygen, Dissolved Region 8      Mill Creek (Prado Area)
LOE ID:	236833
Pollutant:	Oxygen, Dissolved
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	57
Number of Exceedances:	1
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Santa Ana River Regional Monitoring Program data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 1 of 57 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference:	Field, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The dissolved oxygen content of surface waters shall not be depressed below 5 mg/L for waters designated WARM as a result of controllable water quality factors (Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the dates of 2016-05-11 and 2018-03-03
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program

DECISION ID	132274	Region 8
Mill Creek (Prado Area)

Pollutant:	Selenium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132274, Selenium Region 8      Mill Creek (Prado Area)
LOE ID:	234701
Pollutant:	Selenium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the guideline.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	CTR Fresh Water Aquatic Life Protection 4 day Average continuous concentration: selenium 20 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was collected at the Mill Creek at Chino sampling station.
Temporal Representation:	The sample was collected on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132275	Region 8
Mill Creek (Prado Area)

Pollutant:	Silver
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132275, Silver Region 8      Mill Creek (Prado Area)
LOE ID:	234696
Pollutant:	Silver
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Aquatic Life Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the standard.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	The California Toxics Rule cadmium criteria is hardness dependent and ranged as follows: silver 6.04 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was taken in Mill Creek near Chino.
Temporal Representation:	The sample was taken on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data's quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132276	Region 8
Mill Creek (Prado Area)

Pollutant:	Simazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132276, Simazine Region 8      Mill Creek (Prado Area)
LOE ID:	234678
Pollutant:	Simazine
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	USEPA National Recommended Ambient Water Quality Criteria Aquatic Life Protection Instantaneous Max: simazine 10 ppb.
Guideline Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132814	Region 8
Mill Creek (Prado Area)

Pollutant:	Temperature, water
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for conventional or other pollutants (Table 3.2 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. 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.
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 132814, Temperature, water Region 8      Mill Creek (Prado Area)
LOE ID:	237721
Pollutant:	Temperature, water
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Not Recorded
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	2
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed SWAMP RWB8 Monitoring data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Temperature.
Data Reference:	Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	SWAMP
Water Quality Objective/Criterion:	The temperature of waters designated WARM shall not be raised above 90 degrees F June through October or above 78 degrees F during the rest of the year as a result of controllable water quality factors (Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: 801MIC042 (Mill Creek Random Olsen Site 042).
Temporal Representation:	The samples were collected between the dates of 2012-06-19 and 2014-06-09
Environmental Conditions:
QAPP Information:	SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s):	This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
Line of Evidence (LOE) for Decision ID 132814, Temperature, water Region 8      Mill Creek (Prado Area)
LOE ID:	237930
Pollutant:	Temperature, water
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Not Recorded
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	60
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Santa Ana River Regional Monitoring Program data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 0 of 60 samples exceeded the water quality threshold for Temperature.
Data Reference:	Field, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The temperature of waters designated WARM shall not be raised above 90 degrees F June through October or above 78 degrees F during the rest of the year as a result of controllable water quality factors (Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the dates of 2016-05-18 and 2020-03-16
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program
Line of Evidence (LOE) for Decision ID 132814, Temperature, water Region 8      Mill Creek (Prado Area)
LOE ID:	238034
Pollutant:	Temperature, water
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Not Recorded
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Middle Santa Ana River TMDL Monitoring Project data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Temperature.
Data Reference:	Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The temperature of waters designated WARM shall not be raised above 90 degrees F June through October or above 78 degrees F during the rest of the year as a result of controllable water quality factors (Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the dates of 2019-08-06 and 2019-09-03
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program

DECISION ID	132277	Region 8
Mill Creek (Prado Area)

Pollutant:	Thiobencarb/Bolero
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132277, Thiobencarb/Bolero Region 8      Mill Creek (Prado Area)
LOE ID:	234679
Pollutant:	Thiobencarb/Bolero
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not show exceedances of the guidelines.
Data Reference:	Concentrations of Pesticides in the waterbodies in the Santa Ana Region
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	California Dept of Fish and Game: thiobencarb 3.1 ppb.
Guideline Reference:	Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Spatial Representation:	The sample was collected at Mill Creek Near Splatters Duck Club In Prado Wetlands California_USGS NAWQA site.
Temporal Representation:	The sample was collected on 8/8/00.
Environmental Conditions:
QAPP Information:	The data quality is deemed appropriate because it came from the Department of Pesticide Regulation.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132815	Region 8
Mill Creek (Prado Area)

Pollutant:	Toxicity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132815, Toxicity Region 8      Mill Creek (Prado Area)
LOE ID:	238167
Pollutant:	Toxicity
LOE Subgroup:	Toxicity
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	TOXICITY TESTING
Data Used to Assess Water Quality:	0 of the 1 samples collected by SWAMP RWB8 Monitoring for Mill Creek (Prado Area) exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Ceriodaphnia dubia for Young/female, Ceriodaphnia dubia for Survival.
Data Reference:	Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	SWAMP
Water Quality Objective/Criterion:	The concentrations of toxic pollutants in the water column, sediments or biota shall not adversely affect beneficial uses (Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:	The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference:	Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
Spatial Representation:	The samples were collected at monitoring site: 801MIC042 ( Mill Creek Random Olsen Site 042 ).
Temporal Representation:	The samples were collected between the dates of 2012-06-19 and 2012-06-19.
Environmental Conditions:
QAPP Information:	SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s):	This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

DECISION ID	132278	Region 8
Mill Creek (Prado Area)

Pollutant:	Zinc
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 132278, Zinc Region 8      Mill Creek (Prado Area)
LOE ID:	234697
Pollutant:	Zinc
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Warm Freshwater Habitat
Aquatic Life Use:	Warm Freshwater Habitat
Number of Samples:	1
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	The only sample collected did not exceed the standard.
Data Reference:	2006 HCMP Database
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The concentration of toxic substance in the water column, sediments or biota shall not adversely affect beneficial uses (SARWQCB, 1995).
Objective/Criterion Reference:	Water Quality Control Plan for the Santa Ana River Basin
Evaluation Guideline:	The California Toxics Rule cadmium criteria is hardness dependent and ranged as follows: zinc 145.73 ppb.
Guideline Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Spatial Representation:	The sample was taken in Mill Creek near Chino.
Temporal Representation:	The sample was taken on 8/16/2005.
Environmental Conditions:
QAPP Information:	The data's quality is deemed acceptable because it was submitted by an NPDES discharger in accordance with their Monitoring and Reporting Requirements.
QAPP Information Reference(s):	This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

DECISION ID	132813	Region 8
Mill Creek (Prado Area)

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. Three lines of evidence are available in the administrative record to assess this pollutant. Five of the 65 samples exceed the WARM pH objective. 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. Five of the 65 samples exceed the WARM pH objective 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 132813, pH Region 8      Mill Creek (Prado Area)
LOE ID:	237239
Pollutant:	pH
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	2
Number of Exceedances:	1
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed SWAMP RWB8 Monitoring data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 1 of 2 samples exceeded the water quality threshold for pH.
Data Reference:	Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	SWAMP
Water Quality Objective/Criterion:	The pH of inland surface waters shall not be raised above 8.5 or depressed below 6.5 as a result of controllable water quality factors (The Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: 801MIC042 (Mill Creek Random Olsen Site 042).
Temporal Representation:	The samples were collected between the dates of 2012-06-19 and 2014-06-09
Environmental Conditions:
QAPP Information:	SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s):	This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
Line of Evidence (LOE) for Decision ID 132813, pH Region 8      Mill Creek (Prado Area)
LOE ID:	237329
Pollutant:	pH
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	60
Number of Exceedances:	4
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Santa Ana River Regional Monitoring Program data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 4 of 60 samples exceeded the water quality threshold for pH.
Data Reference:	Field, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The pH of inland surface waters shall not be raised above 8.5 or depressed below 6.5 as a result of controllable water quality factors (The Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the dates of 2016-05-18 and 2020-03-16
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program
Line of Evidence (LOE) for Decision ID 132813, pH Region 8      Mill Creek (Prado Area)
LOE ID:	237140
Pollutant:	pH
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	0
Data and Information Type:	PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality:	Water Board staff assessed Middle Santa Ana River TMDL Monitoring Project data for Mill Creek (Prado Area) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for pH.
Data Reference:	Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 8.
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	The pH of inland surface waters shall not be raised above 8.5 or depressed below 6.5 as a result of controllable water quality factors (The Water Quality Control Plan, Santa Ana Basin, Chapter 4 Water Quality Objectives, Inland Surface Waters).
Objective/Criterion Reference:	Water Quality Control Plan, Santa Ana River Basin
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The samples were collected at 1 monitoring site: WW-M6 (Mill-Cucamonga Creek below Wetlands).
Temporal Representation:	The samples were collected between the dates of 2019-08-06 and 2019-09-03
Environmental Conditions:
QAPP Information:	CDM Smith. 2019. Santa Ana River Watershed Bacteria Monitoring Program.
QAPP Information Reference(s):	Santa Ana River Watershed Bacteria Monitoring Program

DECISION ID	77478	Region 8
Mill Creek (Prado Area)

Pollutant:	Nutrients
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2016)
Revision Status	Original
Sources:	A Source Unknown
Expected TMDL Completion Date:	2019
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	There was no new data considered in the 2014 Listing Cycle, this previously made decision will carryover. The following description applies to an earlier Listing Cycle. Regional Board Conclusion: 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed. State Board Review and Conclusion: This Santa Ana Regional Board staff recommended to continue listing this previously listed water body for Nutrients in the centralized database for the assessment. However, the centralized database was not used to generate the final Staff Report for Region 8 and this decision did not get included for Regional Water Board approval. Based on the review of the data and information in the centralized database, State Water Board staff recommends to continue to List this water body-pollutant combination.
Regional Board Decision Recommendation:	This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 77478, Nutrients Region 8      Mill Creek (Prado Area)
LOE ID:	4420
Pollutant:	Nutrients
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Not Recorded
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	0
Number of Exceedances:	0
Data and Information Type:	Not Specified
Data Used to Assess Water Quality:	Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference:	Placeholder reference pre-2006 303(d)
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	Unspecified
Objective/Criterion Reference:	Placeholder reference pre-2006 303(d)
Evaluation Guideline:	Unspecified
Guideline Reference:	Placeholder reference pre-2006 303(d)
Spatial Representation:	Unspecified
Temporal Representation:	Unspecified
Environmental Conditions:	Unspecified
QAPP Information:	Unspecified
QAPP Information Reference(s):

DECISION ID	77479	Region 8
Mill Creek (Prado Area)

Pollutant:	Total Suspended Solids (TSS)
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2016)
Revision Status	Original
Sources:	A Source Unknown
Expected TMDL Completion Date:	2019
Impairment from Pollutant or Pollution:	Pollutant
Regional Board Conclusion:	There was no new data considered in the 2014 Listing Cycle, this previously made decision will carryover. The following description applies to an earlier Listing Cycle. Regional Board Conclusion: 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed. State Board Review and Conclusion: This Santa Ana Regional Board staff recommended to continue listing this previously listed water body for Total Suspended Solids (TSS) in the centralized database for the assessment. However, the centralized database was not used to generate the final Staff Report for Region 8 and this decision did not get included for Regional Water Board approval. Based on the review of the data and information in the centralized database, State Water Board staff recommends to continue to List this water body-pollutant combination.
Regional Board Decision Recommendation:	This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed.
State Board Review of Regional Board Conclusion and Recommendation:
State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

Line of Evidence (LOE) for Decision ID 77479, Total Suspended Solids (TSS) Region 8      Mill Creek (Prado Area)
LOE ID:	4421
Pollutant:	Total Suspended Solids (TSS)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Not Recorded
Beneficial Use:	Warm Freshwater Habitat
Number of Samples:	0
Number of Exceedances:	0
Data and Information Type:	Not Specified
Data Used to Assess Water Quality:	Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference:	Placeholder reference pre-2006 303(d)
SWAMP Data:	Non-SWAMP
Water Quality Objective/Criterion:	Unspecified
Objective/Criterion Reference:	Placeholder reference pre-2006 303(d)
Evaluation Guideline:	Unspecified
Guideline Reference:	Placeholder reference pre-2006 303(d)
Spatial Representation:	Unspecified
Temporal Representation:	Unspecified
Environmental Conditions:	Unspecified
QAPP Information:	Unspecified
QAPP Information Reference(s):