Abstract |
Section 303(d)(1)(C) of the Clean Water Act and the U.S. Environmental Protection Agencys (EPA) implementing regulations (40 Code of Federal Regulations (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 and will not meet standards with the implementation of technology-based effluent limits and other pollution control requirements. A TMDL determines the Loading Capacity (LC)--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) initially included Ward Cove on its 1990 303(d) list of water quality-limited waters for low dissolved oxygen and the presence of residues due to the discharge from Ketchikan Pulp Companys (KPC) dissolving sulfite pulp mill. On the 1994 and subsequent 303(d) lists through 2004, the most recent list, Ward Cove was listed as water quality-limited for three pollutant parameters: residues (wood residues), dissolved gas (dissolved oxygen), and toxic and other deleterious substances (sediment toxicity) (ADEC 2003a). Sediment toxicity was removed from the 2004 303(d) list and placed in category 4b (Other Pollution Controls) because the Record of Decision for the Superfund sediment remediation project (USEPA 2000) for Ward Cove is accepted as a pollution control requirement that will achieve WQS for sediment toxicity (ADEC 2006). This TMDL report includes TMDLs to address the impairments associated with residues and dissolved oxygen; no TMDL will be developed for sediment toxicity. With completion of these TMDLs, the classification of Ward Cove for residues and dissolved oxygen on the next revised Alaska section 303(d) list will be changed to Category 4aTMDL has been completed. |