Water Body State Board Recommendations: Pollutant Listing, Biodiversity Impacts, And Use Support Ratings.pdf

It analyzes multiple water bodies, including: Agua Hedionda Creek, Aliso Creek, Alvarado Creek, Arroyo Trabuco Creek, Boulder Creek, Buena Vista Creek, Chocolate Creek, Chollas Creek, and Cottonwood Creek (Tijuana River watershed).

Key Findings:

Pollutants of Concern: The primary pollutants identified include phosphorus, total nitrogen as N, toxicity (including diazinon), chloride, sediment toxicity, and trash.
Biodiversity Impacts: Many water bodies show evidence of biodiversity impacts, with some experiencing high numbers of exceedances for various indicators.
Listing Decisions: Some water bodies are recommended for listing on the 303(d) list due to excessive pollutant levels, while others are not due to insufficient data or supporting use ratings.
Biodiversity Impacts LOE (Line of Effort) Decisions: Separate decisions are proposed for biodiversity impacts alone, ranging from "Fully Supporting" to "Not Supporting" based on exceedance rates and use support ratings.

Specific Recommendations:

For each water body, the State Board recommends:

Listing or Delisting: Determining whether a water body should be listed as impaired (303(d) list) or removed from the list based on improved water quality.
TMDL (Total Maximum Daily Load) Requirements: Identifying and establishing TMDLs for specific pollutants when necessary.
* Biodiversity Impacts Decisions: Creating separate decisions focusing solely on biodiversity impacts, categorizing them into Situations #2, #4, and #5 based on exceedance rates and use support ratings.

Overall Goal:

The recommendations aim to protect and restore water quality, ensuring these water bodies support healthy ecosystems and beneficial uses while addressing pollution sources and mitigating biodiversity threats.