Cal. Code Regs. tit. 23 § 3939.40
On July 8, 2010, the Los Angeles Regional Water Quality Control Board adopted Resolution No. R10-006, amending the Water Quality Control Plan for the Los Angeles Region by establishing a Total Maximum Daily Load (TMDL) for indicator bacteria in the Santa Clara River (SCR) Estuary and Reaches 3, 5, 6 and 7. The TMDL sets numeric targets for indicator bacteria based on numeric water quality objectives provided in the Basin Plan. The TMDL establishes final waste load allocations (WLAs) for point source discharges, final load allocations (LAs) for nonpoint source discharges, interim LAs for nonpoint source discharges and interim WLAs for city and county Municipal Separate Storm Sewer System (MS4) discharges. Final allocations to achieve the single sample maximum numeric targets are expressed as "allowable exceedance days" and only apply to days in which single sample limits are exceeded and do not apply to days where geometric mean limits are exceeded. No exceedance days of the geometric mean targets are allowed. Allowable exceedance days are further separated into dry weather and wet weather allowances. The TMDL requires the city and county MS4 dischargers and nonpoint source dischargers to achieve the final WLAs and LAs within 11 years for dry weather and 17 years for wet weather. Other point source dischargers must achieve WLAs upon the effective date of the TMDL.
Compliance with the city and county MS4 WLAs is based on the allowable number of exceedance days, except in wet weather, when compliance can alternatively be based on an allowable load of bacteria. Compliance with the city and county MS4 WLAs is assessed using a combination of in-stream and MS4 outfall monitoring. Compliance with the WLAs assigned to other point source dischargers is assessed through permit requirements. Compliance with nonpoint source load allocations is assessed through compliance with waste discharge requirements, waivers, or prohibitions.
Cal. Code Regs. Tit. 23, § 3939.40