Res19 15780 - Laserfiche WebLink

Browse Search

REDWOOD CITY Provisions C.11 and C.12 in the MRP require San Mateo Permittees (San Mateo County and its 20 cities and towns) to reduce estimated PCBs loading by 15 grams/year and estimated mercury loading by 6 grams/year using green infrastructure by June 30, 2020. Regionally, Permittees must also project the load reductions achieved via Green Infrastructure by 2020, 2030, and 2040, showing that collectively, reductions will amount to 3 kg/year of PCBs and 10 kg/year of mercury by 2040. 1.1.1 Further Background on Mercury and PCBs in San Francisco Bay The MRP pollutant -load reduction requirements are driven by Total Maximum Daily Load (TMDL) requirements adopted by the RWQCB for mercury (Resolution No. R2-2004-0082 and 112-2005-0060) and PCBs (Resolution No. 112-2008-0012). Each TMDL allocates allowable annual loads to San Francisco Bay (a Waste Load Allocation, or WLA) from identified sources, including from urban stormwater. The mercury TMDL addresses two water quality objectives. The first, established to protect people who consume fish from the Bay, applies to fish large enough to be consumed by humans. The objective is 0.2 milligrams (mg) of mercury per kilogram (kg) of fish tissue (average wet weight concentration measured in the muscle tissue of fish large enough to be consumed by humans). The second objective, established to protect aquatic organisms and wildlife, applies to small fish (3-5 centimeters in length) commonly consumed by the California least tern, an endangered species. This objective is 0.03 mg mercury per kg fish (average wet weight concentration). To achieve the human health and wildlife fish tissue and bird egg monitoring targets and to attain water quality standards, the Bay -wide suspended sediment mercury concentration target is 0.2 mg of mercury per kg dry sediment. A roughly 50% decrease in sediment, fish tissue, and bird egg mercury concentrations is necessary for Bay Area cities and counties to meet water quality standards. Reductions in sediment mercury concentrations are assumed to result in a proportional reduction in the total amount of mercury in the system, which will result in the achievement of target fish tissue and bird egg concentrations. The PCBs TMDL was developed based on a fish tissue target of 10 nanograms (ng) of PCBs per gram (g) of fish tissue. This target is based on a cancer risk of one case per an exposed population of 100,000 for the 95" percentile San RWC GREEN INFRASTRUCTURE PLAN GREEN INFRASTRUCTURE PLAN 2 JUNE 2019 ATTY/RESO.0075/CC RESO APPROVING THE GREEN INFRASTRUCTURE PLAN — EXHIBIT A RESO. NO. 15780 REV: 06-20-19 PR MUFF NO. 802