On December 3, 2004, the Central Coast Regional Water Quality Control Board (Central Coast Water Board) adopted Resolution No. R3-2004-0142 amending the Water Quality Control Plan for the Central Coast Region (Basin Plan). The amendment revised the Basin Plan by establishing the San Luis Obispo Creek Total Maximum Daily Load and Implementation Plan for Pathogens (TMDL).

The TMDL addresses impairment of San Luis Obispo Creek due to fecal coliform. Current fecal coliform concentration in San Luis Obispo Creek is impairing the water contact recreation and non-contact water recreation beneficial uses (REC-1 and REC-2, respectively.) The TMDL establishes a numeric target for fecal coliform consistent with current Basin Plan objectives protecting both REC-1 and REC-2 beneficial uses. Fecal coliform concentration, based on a minimum of not less than five samples for any 30-day period, shall not exceed a log mean of 200 MPN per 100mL, nor shall more than ten percent of total samples collected during any 30-day period exceed 400 MPN per 100mL. Achieving the numeric target is the responsibility of several entities described in the Basin Plan amendment. An implicit margin of safety is utilized in the TMDL to account for uncertainties.

The Central Coast Water Board is relying on existing regulatory authority to insure implementation actions are carried out by the implementing parties using existing permits. An implementation target of ten years is established for achieving the TMDL. The Central Coast Water Board will track progress towards achieving the TMDL through review of implementation actions and monitoring conducted by the implementing parties. Staff will conduct triennial reviews of implementation actions and monitoring results. If existing efforts are not expected to achieve the TMDL as scheduled (as determined by a triennial review), staff will recommend that additional reporting, monitoring, or implementation efforts be required either through approval by the Executive Officer (e.g., pursuant to California Water Code section 13267 or 13383) or by the Central Coast Water Board (e.g., through revisions of existing permits and/or a Basin Plan amendment).