Cal. Code Regs. tit. 23 § 3939.60
On March 10, 2022, the Los Angeles Regional Water Quality Control Board (Los Angeles Water Board) adopted Resolution No. R22-002, amending the Water Quality Control Plan for the Los Angeles Region (Basin Plan) to incorporate a total maximum daily load (TMDL) for indicator bacteria in Los Cerritos Channel and Estuary, Alamitos Bay, and Colorado Lagoon. The State Water Resources Control Board (State Water Board) approved the amendment under Resolution No. 2022-0053 on December 6, 2022.
The TMDL sets numeric targets for indicator bacteria based on numeric water quality objectives provided in the Basin Plan and Statewide Bacteria Provisions. The TMDL assigns waste load allocations (WLAs) to municipal separate storm sewer system (MS4) discharges and other non-MS4 National Pollutant Discharge Elimination System (NPDES) discharges, and load allocations (LAs) to nonpoint source discharges to attain water quality objectives for bacteria. The water quality objectives are set to protect public health based on the water contact recreation (REC-1) beneficial uses of these waterbodies and will also result in the protection of the non-contact water recreation (REC-2) beneficial use.
There are two types of numeric targets: geometric mean limits calculated over the period of six weeks and a corresponding statistical threshold value (STV) calculated over the period of a calendar month. The applicable STV shall not be exceeded in more than 10 percent of the samples collected in a calendar month, calculated in a static manner. Exceedances of the objectives are frequent during all seasons and conditions and recreational uses of the Los Cerritos Channel and Estuary, Alamitos Bay, and Colorado Lagoon take place during all seasons and conditions, therefore the TMDL allocations are applied equally during all time periods and conditions. No exceedance days of the geometric mean targets are allowed at any time. However, if it is not possible to calculate a geometric mean due to lack of sufficient data, then attainment of the numeric targets shall be determined based on the STV.
The TMDL requires the MS4 dischargers to achieve the final WLAs within 15 years. Other non-MS4 point source dischargers (such as other individual NPDES permittees and general NPDES permittees, including industrial stormwater permittees and construction stormwater permittees) must achieve WLAs upon the effective date of the TMDL. Nonpoint source dischargers, such as owners and/or operators of sanitary sewer collection systems, onsite wastewater treatment systems (septic systems) and marine sanitation devices are to achieve LAs from the effective date of the TMDL. Owners and/or operators of irrigated agricultural land, golf courses and any other nonpoint sources are to achieve LAs within 3 years.
Compliance with the MS4 WLAs is assessed through compliance with MS4 permits. The MS4 WLAs will be implemented by permittees through their Watershed Management Programs, which must be approved by the Los Angeles Water Board. Compliance with the WLAs assigned to non-MS4 point source dischargers is assessed through NPDES permits, with WQBELs in their NPDES permits at the time of permit issuance, modification, or renewal.
Compliance with the LAs is assessed through compliance with the Conditional Waiver for Irrigated Agricultural Lands (Order No. R4-2021-0045-A02 or other successor order) or other appropriate mechanisms consistent with the LAs and the State Water Board's Nonpoint Source Implementation and Enforcement Policy. The LAs for OWTS will be regulated by WDRs or waivers of WDRs consistent with the State Water Board's OWTS Policy. LAs for golf courses will be implemented through WDRs or waivers of WDRs consistent with the State Water Board's Nonpoint Source Implementation and Enforcement Policy. The Nonpoint Source Implementation and Enforcement Policy specifies that the regional water boards have the authority to regulate nonpoint source discharges through WDRs, waivers, and prohibitions.
Cal. Code Regs. Tit. 23, § 3939.60