| |
DECISION ID |
16626 |
| |
| Pollutant: |
Invasive Species |
| 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 |
| |
| 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 watersheds 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. Zero of two sites showed an increase in density of mud snails over a three years of sampling and zero 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: |
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: |
|
| |
| |
| |
| LOE ID: |
28714 |
| |
| Pollutant: |
Invasive Species |
| LOE Subgroup: |
Population/Community Degradation |
| Matrix: |
Water |
| Fraction: |
None |
| |
| Beneficial Use: |
Warm Freshwater Habitat |
| Aquatic Life Use: |
Wildlife Habitat |
| |
| Number of Samples: |
2 |
| Number of Exceedances: |
0 |
| |
| Data and Information Type: |
Benthic macroinvertebrate surveys |
| Data Used to Assess Water Quality: |
A total of zero of two sites showed an increase in density of mud snails over the three years of sampling (2006, 2007, 2008) and zero 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 Triunfo Creek Reach 1: on the trailhead on right side of Ridgeford Dr.; at the corner of Kanan Rd. at Troutdale U.S. of bridge; at the outlet adjacent to Green Willow. |
| Temporal Representation: |
The Trailhead/Ridgeford Dr. and Kanan Rd. at Troutdale sites were sampled in July of 2006, July of 2007 and October of 2008. The Green Willow site was 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.
|