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

Supporting Information

Regional Board 4 - Los Angeles Region

Water Body Name:	Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)
Water Body ID:	CAR4022001219990202161144
Water Body Type:	River & Stream


DECISION ID	150554	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

Pollutant:	Indicator Bacteria
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
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 150554, Indicator Bacteria	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

25839

Pollutant:

Indicator Bacteria

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Other Agencies/Organizations provided monitoring data

Data Used to Assess Water Quality:

Data collected for the Santa Barbara ChannelKeeper Water Quality Monitoring Program (2001 to 2007). A total of zero (0) out of 70 for E. coli samples exceeded the single sample limit (Santa Barbara ChannelKeeper, 2007).

Data Reference:

Santa Barbara Channelkeeper Water Quality Data Submittal and 303(d) List Recommendations

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan bacteria objectives state that to protect water contact recreation in fresh waters individual samples shall not exceed the following limits: fecal coliform density shall not exceed 400/100 ml; and E. coli density shall not exceed 235/100 ml. The bacteria objectives also establish that the geometric means of individual samples shall not exceed the following limits: the fecal coliform density shall not exceed 200/100 ml; and the E. coli density shall not exceed 126/100 ml, as a geometric mean. The bacteria objectives are found in Attachment A of Regional Board Resolution No. 2001-018.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

VR13 sampling site is located at an out-of-use USGS stream gauging station approximately one kilometer downstream of Matilija Dam (Lat 34.483056, Long -119.301944).

Temporal Representation:

Grab samples taken and analyzed on monthly basis from January 2001 to February 2007.

Environmental Conditions:

QAPP Information:

Data collected and analyzed according to the provisions of the Ventura River Watershed Monitoring Program Quality Assurance Project Plan (Santa Barbara Channelkeeper, October 2004).

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan (Santa Barbara Channelkeeper, October 2004)

Line of Evidence (LOE) for Decision ID 150554, Indicator Bacteria	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

302116

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) to determine beneficial use support and the results are as follows: 0 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 4.

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): VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the days of 2018-02-03 and 2018-08-11 .

Environmental Conditions:

QAPP Information:

Santa Barbara Channelkeeper Stream Team Citizen Monitoring Program Data for Ventura, Goleta, and Carpinteria Watersheds. 2016. Ventura River Watershed Monitoring Program Quality Assurance Project Plan.

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan


DECISION ID	149726	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

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

Regional Board Conclusion:	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 149726, Nitrogen, Nitrate	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

302386

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Nitrate as N.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-34) states that: Waters shall not exceed 10 mg/L as nitrate-nitrogen (NO3-N).

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the dates of 2018-08-11 and 2018-08-11

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan


DECISION ID	151888	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	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 151888, Oxygen, Dissolved	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

308278

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) to determine beneficial use support and results are as follows: 0 of 3 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 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-39) states that: The dissolved oxygen content of all surface waters designated as both COLD and SPWN shall not be depressed below 7 mg/L as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the dates of 2018-02-03 and 2018-08-11

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 151888, Oxygen, Dissolved	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

307851

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) to determine beneficial use support and results are as follows: 0 of 3 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 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region (page 3-39) states that: The dissolved oxygen content of all surface waters designated as COLD shall not be depressed below 6 mg/L as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the dates of 2018-02-03 and 2018-08-11

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan


DECISION ID	136370	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	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 136370, Temperature, water	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

266976

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) to determine beneficial use support and results are as follows: 1 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 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: The natural receiving water temperature of all regional waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the dates of 2018-02-03 and 2018-08-11

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 136370, Temperature, water	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

267296

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) to determine beneficial use support and results are as follows: 1 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 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the dates of 2018-02-03 and 2018-08-11

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan

Line of Evidence (LOE) for Decision ID 136370, Temperature, water	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

266698

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) to determine beneficial use support and results are as follows: 1 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 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the dates of 2018-02-03 and 2018-08-11

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan


DECISION ID	136371	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

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

Regional Board Conclusion:	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 136371, Turbidity	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

268120

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Turbidity.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Los Angeles Region states that: Waters shall be free of changes in turbidity that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Turbidities of 25 NTU or greater can cause a reduction in juvenile salmonid growth due to interference with their ability to find food (Sigler et al. 1984).

Guideline Reference:

Effects of chronic turbidity on density and growth of steelheads and coho salmon. Transactions of the American Fisheries Society 113:142-150

Spatial Representation:

The samples were collected at 1 monitoring site: VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the dates of 2018-02-03 and 2018-08-11

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan


DECISION ID	136369	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 136369, pH	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

265348

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Santa Barbara Channelkeeper Stream Team data for Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir) 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 4.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Los Angeles Basin: the pH for inland surface waters, bays, or estuaries shall not be depressed below 6.5 or raised above 8.5 as a result of waste discharges.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: VRW013 (Matilija Creek Downstream of Dam).

Temporal Representation:

The samples were collected between the dates of 2018-02-03 and 2018-08-11

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Ventura River Watershed Monitoring Program Quality Assurance Project Plan


DECISION ID	98238	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

Pollutant:	Benthic Community Effects
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Benthic Community Effects is being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, an additional line of evidence associating the Benthic Community Effects with a water or sediment concentration of pollutants is necessary to assess listing status. Both samples had an IBI score above 40. 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 water 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. Both samples had an IBI score above 40 indicating the Benthic Community is intact. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. The CSCI is applicable statewide, accounts for a much wider range of natural variability, and provides equivalent scoring thresholds in all regions of the state. The CSCI will be used in the future for water quality assessment purposes statewide over the regional indices of biologic integrity (IBIs).

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:	The CSCI is applicable statewide, accounts for a much wider range of natural variability, and provides equivalent scoring thresholds in all regions of the state. The CSCI will be used in the future for water quality assessment purposes statewide over the regional indices of biologic integrity (IBIs).

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 98238, Benthic Community Effects	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

86439

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Two samples were collected from the Ventura River - below Matilija Dam in September 2006 and 2007. Both samples had an IBI score above 40. The scores were 40.04 (2006) and 46 (2007).

Data Reference:

Bioassessment Monitoring Report in Ventura River Watershed for, 2001-2007.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant or animal, or aquatic life. Compliance with this objective will be determined by use of indicator organisms, analysis of species diversity, population density, growth anomalies, bioassays of appropriate duration or other appropriate methods as specified by the State or Regional Board. Region 4 Basin Plan.

Objective/Criterion Reference:

Water Quality Control Plan Los Angeles Region R4 Basin Plan

Evaluation Guideline:

The IBI is a multi-metric assessment that employs biological metrics that respond to a habitat or water quality impairment. Each of the biological metrics measured at a site are converted to an IBI score then summed. These cumulative scores are then ranked. For the Southern California IBI, sites with scores below 40 are considered to have impaired conditions.

Guideline Reference:

Development of a Benthic Index of Biotic Integrity (B-IBI) for Wadeable Streams in Northern Coastal California and its Application to Regional 305(b) Assessment

Spatial Representation:

The samples were collected at station 12 Ventura River - below Matilija Dam, Matilija Creek.

Temporal Representation:

The samples were collected in September 2006 and 2007.

Environmental Conditions:

QAPP Information:

Sampling and laboratory procedures for this survey followed the California Stream Bioassessment Procedure (CSBP 2003) and also incorporated the Southern California Index of Biotic Integrity (IBI) (Ode et al., 2005).

QAPP Information Reference(s):


DECISION ID	70986	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

Pollutant:	Fish Barriers (Fish Passage)
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:	Pollution

Regional Board Conclusion:	303(d) listing decisions made prior to 2006 were not held in an assessment database. The original Listing was flawed because fish barriers is not a pollutant but rather could fall under the definition of pollution. Because the original basis for the decision cannot be determined and no new information has become available this is being removed from the CWA section 303(d) List and placed into Category 4c until more data and information can be collected and assessed.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the impairment is due to a non-pollutant or pollution. This impairment therefore falls under Integrated Report Category 4c.

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 70986, Fish Barriers (Fish Passage)	Region 4
Matilija Creek Reach 1 (Jct. With N. Fork to Reservoir)

LOE ID:

4336

Pollutant:

Fish Barriers (Fish Passage)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

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):