Draft 2008 California 303(d)/305(b) Integrated Report

Supporting Information

Regional Board 4 - Los Angeles Region

Water Body Name: Las Virgenes Creek
Water Body ID: CAR4042201019990201141611
Water Body Type: River & Stream
 
DECISION ID
17207
 
Pollutant: Benthic-Macroinvertebrate Bioassessments
Final Listing Decision: List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Sources: Nonpoint Source | Point Source
Expected TMDL Completion Date: 2021
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for the section 303(d) list under section 3.9 of the Listing Policy. Under section 3.9, waters are listed when a bioassessment shows diminished numbers of species or other metrics (compared to a reference site) and it is associated with another pollutant.

Eight lines of evidence are available in the administrative record to assess this pollutant. Benthic macroinvertebrates as measured by Southern California IBI (index of biological integrity) in Las Virgenes Creek were poor and very poor at two sites in winter of 2005; very poor and poor at two sites in the spring and poor and very poor at two sites in the fall indicating impairment of benthic community structure. This impairment is associated with impairment for Invasive Species, Nutrients(algae), Sedimentation/Siltation, Selenium, and Trash

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification to place the water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. There is at least one bioassessment sample (Index of Biological Integrity score) to satisfy Section 3.9
4. The impairment is associated with another pollutant in the waterbody to satisfy Section 3.9.
5. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be added to the section 303(d) list because applicable water quality standards are not being attained.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 17207
 
LOE ID: 30175
 
Pollutant: Invasive Species
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Fish Migration | Fish Spawning | Preservation of Rare & Endangered Species | Wetland Habitat | Wildlife Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: The IBI scores at these sites ranked in the “very poor” and “poor” range (12 and 25) in the spring and “poor” and “very poor” range (11 and 23) in the fall.
Data Reference: Malibu Watershed 2005 Bioassessment Monitoring Report. (2005) The Malibu Creek Watershed Monitoring Program City of Calabasas, Environmental Services Division. Submitted by: Aquatic Bioassay and Consulting Laboratories.
 
Water Quality Objective/Criterion: The Basin Plan states that: "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.”
Objective/Criterion Reference: Water Quality Control Plan Los Angeles Region R4 Basin Plan
  Basin Plan Amendments to the Water Quality Control Plan Los Angeles Region R4 Basin Plan as of 02/02/2009
 
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 as very good (80-100), good (60-79), fair (40-49), poor (20-39) and very poor (0-19) habitat conditions. Sites with scores below 39 are considered to have impaired conditions.
Guideline Reference: A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams. Environmental Management Vol. 35, No. 4, pp. 493-504.
 
Spatial Representation: Two sites in Las Virgenes Creek were sampled, LV1 at 34° 10.108' N 118° 42.155' W and LV2 at 34° 07.507' N 118° 42.494' W
Temporal Representation: Sites were sampled in Spring and Fall of 2005
Environmental Conditions: Benthic macroinvertebrate populations and IBI scores may also be affected by a wide range of anthropogenic stressors.
QAPP Information: Data was collected in compliance with California Stream Bioassessment Procedure.
QAPP Information Reference(s): California Stream Bioassessment Procedure (Protocol Brief for Biological and Physical/Habitat Assessment in Wadeable Streams) California Department of Fish and Game Water Pollution Control Laboratory Aquatic Bioassessment Laboratory Revision Date - December, 2003
 
LOE ID: 30174
 
Pollutant: Invasive Species
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Fish Migration | Fish Spawning | Preservation of Rare & Endangered Species | Wetland Habitat | Wildlife Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: Two sites sampled in 2005 IBI scores were calculated at 17 category “very poor” and 34, category “poor.”
Data Reference: Malibu Bioassessment Winter 2005
 
Water Quality Objective/Criterion: The Basin Plan states that: "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.”
Objective/Criterion Reference: Water Quality Control Plan Los Angeles Region R4 Basin Plan
  Basin Plan Amendments to the Water Quality Control Plan Los Angeles Region R4 Basin Plan as of 02/02/2009
 
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 as very good (80-100), good (60-79), fair (40-49), poor (20-39) and very poor (0-19) habitat conditions. Sites with scores below 39 are considered to have impaired conditions.
Guideline Reference: A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams. Environmental Management Vol. 35, No. 4, pp. 493-504.
 
Spatial Representation: Two sites in Las Virgenes Creek were sampled, LV5 and LV9.
Temporal Representation: Sites were sampled in winter of 2005.
Environmental Conditions: Benthic macroinvertebrate populations and IBI scores may also be affected by a wide range of anthropogenic stressors.
QAPP Information: Data was collected in compliance with California Stream Bioassessment Procedure. Collection procedures were audited by California Department of Fish and Game in 2006.
QAPP Information Reference(s): California Stream Bioassessment Procedure (Protocol Brief for Biological and Physical/Habitat Assessment in Wadeable Streams) California Department of Fish and Game Water Pollution Control Laboratory Aquatic Bioassessment Laboratory Revision Date - December, 2003
  California Stream Bioassessment Procedure Biological and Physical Habitat Field Audit
 
LOE ID: 28703
 
Pollutant: Invasive Species
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Fish Migration | Fish Spawning | Preservation of Rare & Endangered Species | Wetland Habitat | Wildlife Habitat
 
Number of Samples: 5
Number of Exceedances: 3
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: A total of three of five sites showed an increase in density of mud snails over the three years of sampling (2006, 2007, 2008) and six of 10 sites sampled showed medium or high densities of mud snail in 2008.
Data Reference: New Zealand Mudsnail Surveys July 2006, July 2007 and October 2008 Santa Monica Mountains. Santa Monica Bay Restoration Commission / Santa Monica Baykeeper.
 
Water Quality Objective/Criterion: The Basin Plan states that: "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.”
Objective/Criterion Reference: Water Quality Control Plan Los Angeles Region R4 Basin Plan
  Basin Plan Amendments to the Water Quality Control Plan Los Angeles Region R4 Basin Plan as of 02/02/2009
 
Evaluation Guideline: Presence of high densities and increasing densities. While quantitative and predictive research continues, due to its ability to attain extremely high densities, the impacts of the mudsnails on aquatic ecosystems where it occurs in the western U.S. are large and include: decreased densities of native macroinvertebrates and reduced food resources; decreased whole-stream algal production; poor food source in that mudsnails are much more difficult to digest, with their hard shells and operculum than are the thin-shelled, native pulmonate snails that do not have opercula or than soft-bodied, aquatic insect larvae.
Guideline Reference: The New Zealand Mudsnail Invades the Western United States. Aquatic Nuisance Species Digest Volume 4 No. 4.
 
Spatial Representation: 10 sites were sampled in the following locations in Las Virgenes Creek: end of Las Virgenes Rd; SMMC open space; open space in the 2nd crossing W of L.V. Creek; dead end of Las Virgenes Rd. gate on right side; Lost Hills Rd. Bridge at the Starbuck’s parking lot; Apartments upstream of RCD Stream Restoration; RCD Stream Restoration site on Lost Hills Rd; De’Anza Park, on the path down to creek; White Oak Farms Bridge; Upstream Crags Rd. crossing MCSP; D.S.
Temporal Representation: Five sites were sampled in July of 2006 and the additional five sites were sampled in July of 2007 and October of 2008.
Environmental Conditions:
QAPP Information: Data was collected as detailed in the Santa Monica Bay Restoration Commission and Santa Monica Baykeeper New Zealand Mudsnail Surveys.
QAPP Information Reference(s): New Zealand Mudsnail Surveys July 2006, July 2007 and October 2008 Santa Monica Mountains. Santa Monica Bay Restoration Commission / Santa Monica Baykeeper.
 
LOE ID: 28587
 
Pollutant: Nutrients (Algae)
LOE Subgroup: Narrative Description Data
Matrix: Not Specified
Fraction: None
 
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: A TMDL has been established for this water segment-pollutant combination. The Malibu Creek Watershed Nutrient TMDL was established by USEPA on March 21, 2003.
Data Reference: Staff report, appendix, and letter to SWRCB and Los Angeles RWQCB establishing a TMDL for Nutrients in the Malibu Creek Watershed.
 
Water Quality Objective/Criterion:
Objective/Criterion Reference:
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation:
Temporal Representation:
Environmental Conditions:
QAPP Information: QA information unavailable.
QAPP Information Reference(s):
 
LOE ID: 3887
 
Pollutant: Trash
LOE Subgroup: Visual
Matrix: Not Specified
Fraction: Not Recorded
 
Beneficial Use: Non-Contact Recreation
 
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)
 
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):
 
LOE ID: 3886
 
Pollutant: Selenium
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)
 
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):
 
LOE ID: 3882
 
Pollutant: Nutrients (Algae)
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)
 
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):
 
LOE ID: 3885
 
Pollutant: Sedimentation/Siltation
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)
 
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
16621
 
Pollutant: Invasive Species
Final Listing Decision: List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Sources: Nonpoint Source | Point Source
Expected TMDL Completion Date: 2021
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.10 of the Listing Policy. Under section 3.10, waters are listed when a declining trend in water quality is substantiated.

Three lines of evidence are available in the administrative record to assess this pollutant. Three of 5 sites showed an increase in density of mud snails over the three years of sampling (2006, 2007, 2008) and 6 out of 10 sites sampled showed medium or high densities of mud snail in 2008.

At high numbers, mud snails can completely cover a stream bed and damage local stream ecosystems. The colonies outcompete native aquatic invertebrates that the watershed’s fish and amphibians rely on for food, disrupting the entire food web.

Benthic macroinvertebrates as measured by Southern California IBI (index of biological integrity) in Las Virgenes Creek were poor or very poor in 2005 indicating impairment of benthic community structure.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. Data was collected over a three years time frame and a baseline condition of zero abundance of the invasive species was used.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 16621
 
LOE ID: 30174
 
Pollutant: Invasive Species
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Fish Migration | Fish Spawning | Preservation of Rare & Endangered Species | Wetland Habitat | Wildlife Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: Two sites sampled in 2005 IBI scores were calculated at 17 category “very poor” and 34, category “poor.”
Data Reference: Malibu Bioassessment Winter 2005
 
Water Quality Objective/Criterion: The Basin Plan states that: "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.”
Objective/Criterion Reference: Water Quality Control Plan Los Angeles Region R4 Basin Plan
  Basin Plan Amendments to the Water Quality Control Plan Los Angeles Region R4 Basin Plan as of 02/02/2009
 
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 as very good (80-100), good (60-79), fair (40-49), poor (20-39) and very poor (0-19) habitat conditions. Sites with scores below 39 are considered to have impaired conditions.
Guideline Reference: A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams. Environmental Management Vol. 35, No. 4, pp. 493-504.
 
Spatial Representation: Two sites in Las Virgenes Creek were sampled, LV5 and LV9.
Temporal Representation: Sites were sampled in winter of 2005.
Environmental Conditions: Benthic macroinvertebrate populations and IBI scores may also be affected by a wide range of anthropogenic stressors.
QAPP Information: Data was collected in compliance with California Stream Bioassessment Procedure. Collection procedures were audited by California Department of Fish and Game in 2006.
QAPP Information Reference(s): California Stream Bioassessment Procedure (Protocol Brief for Biological and Physical/Habitat Assessment in Wadeable Streams) California Department of Fish and Game Water Pollution Control Laboratory Aquatic Bioassessment Laboratory Revision Date - December, 2003
  California Stream Bioassessment Procedure Biological and Physical Habitat Field Audit
 
LOE ID: 28703
 
Pollutant: Invasive Species
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Fish Migration | Fish Spawning | Preservation of Rare & Endangered Species | Wetland Habitat | Wildlife Habitat
 
Number of Samples: 5
Number of Exceedances: 3
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: A total of three of five sites showed an increase in density of mud snails over the three years of sampling (2006, 2007, 2008) and six of 10 sites sampled showed medium or high densities of mud snail in 2008.
Data Reference: New Zealand Mudsnail Surveys July 2006, July 2007 and October 2008 Santa Monica Mountains. Santa Monica Bay Restoration Commission / Santa Monica Baykeeper.
 
Water Quality Objective/Criterion: The Basin Plan states that: "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.”
Objective/Criterion Reference: Water Quality Control Plan Los Angeles Region R4 Basin Plan
  Basin Plan Amendments to the Water Quality Control Plan Los Angeles Region R4 Basin Plan as of 02/02/2009
 
Evaluation Guideline: Presence of high densities and increasing densities. While quantitative and predictive research continues, due to its ability to attain extremely high densities, the impacts of the mudsnails on aquatic ecosystems where it occurs in the western U.S. are large and include: decreased densities of native macroinvertebrates and reduced food resources; decreased whole-stream algal production; poor food source in that mudsnails are much more difficult to digest, with their hard shells and operculum than are the thin-shelled, native pulmonate snails that do not have opercula or than soft-bodied, aquatic insect larvae.
Guideline Reference: The New Zealand Mudsnail Invades the Western United States. Aquatic Nuisance Species Digest Volume 4 No. 4.
 
Spatial Representation: 10 sites were sampled in the following locations in Las Virgenes Creek: end of Las Virgenes Rd; SMMC open space; open space in the 2nd crossing W of L.V. Creek; dead end of Las Virgenes Rd. gate on right side; Lost Hills Rd. Bridge at the Starbuck’s parking lot; Apartments upstream of RCD Stream Restoration; RCD Stream Restoration site on Lost Hills Rd; De’Anza Park, on the path down to creek; White Oak Farms Bridge; Upstream Crags Rd. crossing MCSP; D.S.
Temporal Representation: Five sites were sampled in July of 2006 and the additional five sites were sampled in July of 2007 and October of 2008.
Environmental Conditions:
QAPP Information: Data was collected as detailed in the Santa Monica Bay Restoration Commission and Santa Monica Baykeeper New Zealand Mudsnail Surveys.
QAPP Information Reference(s): New Zealand Mudsnail Surveys July 2006, July 2007 and October 2008 Santa Monica Mountains. Santa Monica Bay Restoration Commission / Santa Monica Baykeeper.
 
LOE ID: 30175
 
Pollutant: Invasive Species
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Fish Migration | Fish Spawning | Preservation of Rare & Endangered Species | Wetland Habitat | Wildlife Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: The IBI scores at these sites ranked in the “very poor” and “poor” range (12 and 25) in the spring and “poor” and “very poor” range (11 and 23) in the fall.
Data Reference: Malibu Watershed 2005 Bioassessment Monitoring Report. (2005) The Malibu Creek Watershed Monitoring Program City of Calabasas, Environmental Services Division. Submitted by: Aquatic Bioassay and Consulting Laboratories.
 
Water Quality Objective/Criterion: The Basin Plan states that: "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.”
Objective/Criterion Reference: Water Quality Control Plan Los Angeles Region R4 Basin Plan
  Basin Plan Amendments to the Water Quality Control Plan Los Angeles Region R4 Basin Plan as of 02/02/2009
 
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 as very good (80-100), good (60-79), fair (40-49), poor (20-39) and very poor (0-19) habitat conditions. Sites with scores below 39 are considered to have impaired conditions.
Guideline Reference: A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams. Environmental Management Vol. 35, No. 4, pp. 493-504.
 
Spatial Representation: Two sites in Las Virgenes Creek were sampled, LV1 at 34° 10.108' N 118° 42.155' W and LV2 at 34° 07.507' N 118° 42.494' W
Temporal Representation: Sites were sampled in Spring and Fall of 2005
Environmental Conditions: Benthic macroinvertebrate populations and IBI scores may also be affected by a wide range of anthropogenic stressors.
QAPP Information: Data was collected in compliance with California Stream Bioassessment Procedure.
QAPP Information Reference(s): California Stream Bioassessment Procedure (Protocol Brief for Biological and Physical/Habitat Assessment in Wadeable Streams) California Department of Fish and Game Water Pollution Control Laboratory Aquatic Bioassessment Laboratory Revision Date - December, 2003
 
DECISION ID
7059
 
Pollutant: Nutrients (Algae)
Final Listing Decision: List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2006)
Revision Status Revised
Sources: Agriculture-animal | Atmospheric Deposition | Golf course activities | Groundwater Loadings | Irrigated Crop Production | Major Municipal Point Source-dry and/or wet weather discharge | Onsite Wastewater Systems (Septic Tanks) | Urban Runoff/Storm Sewers
TMDL Name: Malibu Creek Nutrients
TMDL Project Code: 239
Date TMDL Approved by USEPA: 03/21/2003
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for removal on the section 303(d) list under sections 2.2 of the Listing Policy. Under 2.2 of the Policy, a minimum of one line of evidence is needed to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant.

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 section 303(d) list. There is sufficient justification to place it in the Being Addressed portion of the 303(d) list because a TMDL has been established by USEPA, and is expected to result in attainment of the standard.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the Water Quality Limited Segments Being Addressed category of the section 303(d) list because a TMDL has been established by USEPA, and applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7059
 
LOE ID: 28587
 
Pollutant: Nutrients (Algae)
LOE Subgroup: Narrative Description Data
Matrix: Not Specified
Fraction: None
 
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: A TMDL has been established for this water segment-pollutant combination. The Malibu Creek Watershed Nutrient TMDL was established by USEPA on March 21, 2003.
Data Reference: Staff report, appendix, and letter to SWRCB and Los Angeles RWQCB establishing a TMDL for Nutrients in the Malibu Creek Watershed.
 
Water Quality Objective/Criterion:
Objective/Criterion Reference:
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation:
Temporal Representation:
Environmental Conditions:
QAPP Information: QA information unavailable.
QAPP Information Reference(s):
 
LOE ID: 3882
 
Pollutant: Nutrients (Algae)
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)
 
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
7108
 
Pollutant: Organic Enrichment/Low Dissolved Oxygen
Final Listing Decision: List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2006)
Revision Status Revised
Sources: Agriculture-animal | Atmospheric Deposition | Golf course activities | Groundwater Loadings | Irrigated Crop Production | Major Municipal Point Source-dry and/or wet weather discharge | Onsite Wastewater Systems (Septic Tanks) | Urban Runoff/Storm Sewers
TMDL Name: Malibu Creek Nutrients
TMDL Project Code: 239
Date TMDL Approved by USEPA: 03/21/2003
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for removal on the section 303(d) list under sections 2.2 of the Listing Policy. Under 2.2 of the Policy, a minimum of one line of evidence is needed to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant.

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 section 303(d) list. There is sufficient justification to place it in the Being Addressed portion of the 303(d) list because a TMDL has been established by USEPA, and is expected to result in attainment of the standard.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the Water Quality Limited Segments Being Addressed category of the section 303(d) list because a TMDL has been established by USEPA, and applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7108
 
LOE ID: 3883
 
Pollutant: Organic Enrichment/Low Dissolved Oxygen
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)
 
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):
 
LOE ID: 28602
 
Pollutant: Organic Enrichment/Low Dissolved Oxygen
LOE Subgroup: Narrative Description Data
Matrix: Not Specified
Fraction: None
 
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: A TMDL has been established for this water segment-pollutant combination. The Malibu Creek Watershed Nutrient TMDL was established by USEPA on March 21, 2003.
Data Reference: Staff report, appendix, and letter to SWRCB and Los Angeles RWQCB establishing a TMDL for Nutrients in the Malibu Creek Watershed.
 
Water Quality Objective/Criterion:
Objective/Criterion Reference:
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation:
Temporal Representation:
Environmental Conditions:
QAPP Information: QA information unavailable.
QAPP Information Reference(s):
 
DECISION ID
7109
 
Pollutant: Scum/Foam-unnatural
Final Listing Decision: List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2006)
Revision Status Revised
Sources: Agriculture-animal | Atmospheric Deposition | Golf course activities | Groundwater Loadings | Irrigated Crop Production | Major Municipal Point Source-dry and/or wet weather discharge | Onsite Wastewater Systems (Septic Tanks) | Urban Runoff/Storm Sewers
TMDL Name: Malibu Creek Nutrients
TMDL Project Code: 239
Date TMDL Approved by USEPA: 03/21/2003
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for removal on the section 303(d) list under sections 2.2 of the Listing Policy. Under 2.2 of the Policy, a minimum of one line of evidence is needed to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant.

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 section 303(d) list. There is sufficient justification to place it in the Being Addressed portion of the 303(d) list because a TMDL has been established by USEPA, and is expected to result in attainment of the standard.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the Water Quality Limited Segments Being Addressed category of the section 303(d) list because a TMDL has been established by USEPA, and applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7109
 
LOE ID: 3884
 
Pollutant: Scum/Foam-unnatural
LOE Subgroup: Pollutant-Nuisance
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Non-Contact Recreation
 
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)
 
Water Quality Objective/Criterion:
Objective/Criterion Reference: Placeholder reference pre-2006 303(d)
 
Evaluation Guideline:
Guideline Reference: Placeholder reference pre-2006 303(d)
 
Spatial Representation: Unspecified
Temporal Representation: Unspecified
Environmental Conditions: Unspecified
QAPP Information: Unspecified
QAPP Information Reference(s):
 
LOE ID: 28597
 
Pollutant: Scum/Foam-unnatural
LOE Subgroup: Narrative Description Data
Matrix: Not Specified
Fraction: None
 
Beneficial Use: Non-Contact Recreation
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Not Specified
Data Used to Assess Water Quality: A TMDL has been established for this water segment-pollutant combination. The Malibu Creek Watershed Nutrient TMDL was established by USEPA on March 21, 2003.
Data Reference: Staff report, appendix, and letter to SWRCB and Los Angeles RWQCB establishing a TMDL for Nutrients in the Malibu Creek Watershed.
 
Water Quality Objective/Criterion:
Objective/Criterion Reference:
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation:
Temporal Representation:
Environmental Conditions:
QAPP Information: QA information unavailable.
QAPP Information Reference(s):