Cal. Code Regs. tit. 23 § 3989.1
The TMDL addresses toxicity in Chollas Creek caused by the pesticide diazinon. The concentration-based numeric targets and TMDL for diazinon were set equal to the California Department of Fish and Game freshwater Water Quality Criteria for diazinon. The acute Water Quality Criterion of 0.08 µg/L protects aquatic life from short-term exposure to diazinon, while the chronic criterion of 0.05 µg/L protects aquatic life from long-term diazinon exposure. The concentration-based wasteload and load allocations of this TMDL were assigned equally to all diazinon discharge sources in the Chollas Creek Watershed. All allocations were set at 90 percent of the numeric targets resulting in a diazinon allocation equal to 0.072 µg/L under acute exposure conditions (one-hour average) and a diazinon allocation of 0.045 µg/L under chronic exposure conditions (four-day average). Frequency of allowed exceedances are set at once every three years on the average. These allocations include an explicit 10 percent margin of safety to account for uncertainties in the TMDL analysis and represent approximately a 90 percent reduction from current loads.
The responsible parties are the Cities of San Diego, Lemon Grove, and La Mesa, the San Diego Unified Port District, the County of San Diego, and the California Department of Transportation. These entities are responsible for implementation of the TMDL and for reduction of their diazinon discharges. The Regional Board will revise the San Diego Municipal Separate Storm Sewer System Permit to make it consistent with the wasteload and load allocation part of this TMDL. Compliance with numeric limitations for diazinon will be required in accordance with a phased schedule of compliance.
Cal. Code Regs. Tit. 23, § 3989.1