Regional Board Resolution No. R3-2002-0051, adopted on May 16, 2003 by the Central Coast Regional Water Quality Control Board (Regional Board), modified the regulatory provisions of the Water Quality Control Plan for the Central Coast Region (Basin Plan) by establishing a Total Maximum Daily Load (TMDL) for Sediment in Chorro Creek, Los Osos Creek, and the Morro Bay Estuary, adopting numeric targets for sediment, and adopting an implementation plan to achieve the TMDL.

This Basin Plan amendment establishes the TMDL for sediment in Chorro Creek at 30,020 tons/year; in Los Osos Creek at 4,864 tons/year; and in the Morro Bay Estuary at 24,885 tons/year. An implicit margin of safety was incorporated into the TMDL through the use of conservative assumptions throughout the sediment source analysis and characterization of beneficial uses impacts. The Regional Board set load allocations for subwatersheds based on fifty percent reductions in erosion. The amendment establishes numeric targets for streambed sediment characteristics known to be supportive of the beneficial uses protecting anadromous fish and for the volume of tidal prism in the Morro Bay Estuary. The numeric targets interpret narrative water quality objectives for sediment in the Basin Plan. The Regional Board will evaluate the TMDL by monitoring numeric targets and tracking implementation actions. Implementation emphasizes the activities of the Morro Bay National Estuary Program, Coastal San Luis Resources Conservation District, and other public and private groups to implement self-determined activities identified in the amendment language. If self-determined actions have not been completed at the end of the third year of implementation, staff will develop a regulatory approach (rather than a self-determined approach) and present a revised implementation plan to the Regional Board as a Basin Plan amendment. This Basin Plan amendment establishes a 50-year implementation period to achieve the TMDL. Revision of the TMDL, the numeric targets, or the implementation strategy would be considered through the Basin Plan amendment process.