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Published byDwayne Rutley Modified over 10 years ago
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Dredging, Wetlands Creation, & Ecosystem Protection: Finding the Right Balance for SF Bay LTMS Methylmercury and Dredging Symposium January 28, 2010 Dyan Whyte, Assistant Executive Officer
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Framework for addressing Mercury in SF Bay is the TMDL
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Established Water Quality Objectives for SF Bay 0.2 ppm mercury in large predator fish 0.03 ppm mercury in prey fish California least tern
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TMDL Implementation Dredging and In-Bay Disposal Load Allocation = Zero Load Allocation = Zero Implement LTMS Implement LTMS Restrictions on In-Bay Disposal Restrictions on In-Bay Disposal Sed. Hg conc. < ambient (0.53 ppm) Sed. Hg conc. < ambient (0.53 ppm) Operations shall not cause an increase in Hg bioavailability Operations shall not cause an increase in Hg bioavailability
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TMDL Implementation Wetlands Creation & Restoration No net increase in Hg or MeHg loads No net increase in Hg or MeHg loads Requirements in WDRs/401 WQ Certs to manage existing wetlands and ensure newly constructed wetlands are designed to minimize MeHg production and biological uptake Requirements in WDRs/401 WQ Certs to manage existing wetlands and ensure newly constructed wetlands are designed to minimize MeHg production and biological uptake Pre- and post-restoration monitoring Pre- and post-restoration monitoring Adaptive Implementation Adaptive Implementation
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Dredging + Desire for More Wetlands = Beneficial Reuse Cover and Non-cover reuse requirements Non-cover subject to strict controls Min 3 feet below surface at anaerobic depths below tide line Min 200 feet from future higher order channels
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Current Approach to Adaptive Management Biosentinels Baseline Triggers Evaluate management actions Learning project by project
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Discussion Topics RMP Hg strategy asks the right questions, is enough being done to answer them? Identifying the right biosentinels & triggers is critical How reversible do actions need to be? Regional Monitoring Approach – Is there a need to formalize?
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