Cal. Code Regs. tit. 23 § 3939.35
The Los Angeles Regional Water Quality Control Board (Regional Board) adopted Resolution No. R08-006 on May 1, 2008, which modified the regulatory provisions of the Water Quality Control Plan for the Los Angeles Region (Basin Plan) by (1) revising the Table of Contents, (2) adding introductory text for Chapter 7 (Total Maximum Daily Loads), and (3) establishing a Total Maximum Daily Load (TMDL) for Eutrophic, Algae, Ammonia, and Odors (Nutrient) in Machado Lake.
The Basin Plan amendment establishes numeric targets for total phosphorus, total nitrogen (TKN+NO3-N+NO2-N), ammonia -- N (chronic and acute), dissolved oxygen, and chlorophyll a. These numeric targets are set to achieve the applicable Water Quality Objectives, which are Biostimulatory Substances, Taste and Odor, Dissolved Oxygen, and Ammonia. The TMDL waste load allocations (WLAs) for point source discharges and load allocations (LAs) for nonpoint source discharges are established to attain the TMDL numeric targets. Waste load allocations are assigned to urban stormwater dischargers in both wet and dry weather. The final waste load allocations are assigned as concentration based allocations of 0.1 mg/L and 1.0 mg/L as monthly averages for total phosphorus and total nitrogen (TKN+NO3-N+NO2-N), respectively. Load allocations are assigned for nonpoint sources discharges to the lake, primarily internal nutrient loading from the lake sediments. The final load allocations for internal loading are concentration based allocations for 0.1 mg/L and 1.0 mg/L as monthly averages for total phosphorus and total nitrogen (TKN+NO3-N+NO2-N), respectively.
The regulatory mechanisms used to implement the TMDL include the Los Angeles County municipal separate storm sewer system (MS4) permit, the Caltrans stormwater permit, the general industrial stormwater NPDES permit, and the general construction stormwater NPDES permit. Nonpoint sources are regulated through a Memorandum of Agreement (MOA) between the responsible parties and the Regional Board Executive Officer. The MOA shall comply with the Water Quality Control Policy for Addressing Impaired Waters: Regulatory Structure and Options ("Policy"), including part II section 2 c ii and related provisions. The implementation of the MOA must result in attainment of the TMDL load allocations. If the MOA does not result in the attainment of the TMDL load allocations, the MOA will be rescinded and the load allocations shall be implemented through a clean up and abatement order.
The TMDL requires stormwater permittees to achieve interim waste load allocations upon the effective date of the TMDL and final waste load allocations 9.5 years from the effective date of the TMDL. The TMDL requires responsible parties assigned load allocations to achieve interim load allocations upon the effective date of the TMDL and final load allocations 9.5 years from the effective date of the TMDL. The TMDL allows for special studies, which are required to be completed within 6 years of the effective date. The Regional Board shall reconsider the TMDL 7.5 years from the effective date based on the results of special studies and water quality monitoring.
Cal. Code Regs. Tit. 23, § 3939.35