Abstract |
Section 303(d)(1)(C) of the Clean Water Act and the U.S. Environmental Protection Agencys (EPA) implementing regulations (40 CFR Part 130) require that a Total Maximum Daily Load (TMDL) be established to achieve state water quality standards (WQS) when a waterbody is water quality-limited for a specific pollutant and will not meet WQS with the implementation of technology-based effluent limitations and other pollution control requirements. A TMDL identifies the amount of a pollutant that a waterbody can receive while still meeting WQS, and establishes discharge limits for existing and future discharge sources of the pollutant, including an appropriate margin of safety (MOS). Discharge limits for point sources are called wasteload allocations (WLAs); discharge limits for nonpoint sources are called load allocations (LAs). The Alaska Department of Environmental Conservation (ADEC) included Thorne Bay from 1994 through 2002 on Alaskas 303(d) list of water quality-limited waters (impaired waters) for bark and wood debris from in-water log transfer and log storage activities that accumulated on the bottom in a portion of the northern end of Thorne Bay. These facilities ceased operation in 2000 and are not anticipated to resume operation. The States 2004 303(d) list (issued in 2006) removed the former log storage area from the impaired list but maintained listing of the former log transfer marine area at the head of the bay (ADEC, 2006). This report presents a TMDL to address impairments associated with wood residues (bark and wood debris) at the former log transfer marine area at the head of the bay but not at the former log storage area. |