Total Maximum Daily Load (TMDL) for Settleable Solid Residues in the Waters of South Unalaska Bay, Alaska

摘要

Section 303(d)(1)(C) of the Clean Water Act (CWA), and the U.S. Environmental Protection Agency's (EPA) implementing regulations (40 CFR Part 130) require the establishment of Total Maximum Daily Loads (TMDL)s for waters for which the technology-based controls required by Section 301 of the CWA and other legally required pollution control mechanisms are inadequate to ensure the achievement of state water quality standards. A TMDL is an implementation plan which identifies the degree of pollution control needed to attain and maintain compliance with state water quality standards using an appropriate margin of safety (EPA 1991). The focus of the implementation plan is the reduction of pollutant inputs to a level (or 'daily load') that will meet the water quality standard and thus fully support the beneficial uses of a given waterbody. The mechanisms used to address water quality problems through the TMDL process can include effluent limits, best management practices and monitoring requirements in National Pollutant Discharge Elimination (NPDES) permits.