EPA recently released a document called "TMDLs Where Mercury Loadings are Predominantly from Air Deposition" to assist states in developing TMDLs for mercury-impaired waters under Clean Water Act section 303(d). This document describes considerations when developing mercury total maximum daily loads (TMDLs) in order to address the required and recommended TMDL elements discussed in existing guidance. The document (also referred to as a mercury TMDL ?checklist?) includes factors to consider when addressing TMDL elements on different geographic scales, such as waterbody, regional, and multi-state. The "checklist" builds on approaches in approved mercury TMDLs.
This effort is part of EPA's multi-pronged approach to listing mercury-impaired waters and developing mercury TMDLs. Recent efforts include revising strategic plan reporting provisions to more specifically account for mercury-impaired waters in tracking waterbody restoration. EPA also issued a memo in 2007 on the "5m" subcategory for listing waters impaired by mercury from air deposition (see http://www.epa.gov/owow/tmdl/mercury5m/ ). For such waters, states may defer the development of mercury TMDLs where a comprehensive state mercury reduction program has been put in place.
The cover memo and checklist are available respectively at http://www.epa.gov/owow/tmdl/pdf/cover_memo_mercury_tmdl_elements.pdf and http://www.epa.gov/owow/tmdl/pdf/document_mercury_tmdl_elements.pdf .
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