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

Supporting Information

Regional Board 4 - Los Angeles Region

Water Body Name: Solstice Canyon Creek
Water Body ID: CAR4043200020050623113649
Water Body Type: River & Stream
 
DECISION ID
16622
 
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.

One line of evidence is available in the administrative record to assess this pollutant.

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.

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.
3. One of one sites showed an increase in density of mud snails over a three years of sampling and one of three sites sampled showed medium or high densities of mud snail in 2008.
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:
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 16622
 
LOE ID: 28704
 
Pollutant: Invasive Species
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Fish Migration | Fish Spawning | Wildlife Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: One of one sites showed an increase in density of mud snails over the three years of sampling (2006, 2007, 2008) and one of three 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: Three sites were sampled in the following locations in Solstice Canyon Creek: NPS U.S. wood bridge; U.S. 2nd bridge; and1st bridge-PCH culvert.
Temporal Representation: The 1st bridge-PCH culvert site was sampled in in July of 2006, July of 2007 and October of 2008. The other two sites were sampled 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.