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BackgroundThe 2004 Water Quality Assessment, Category 5 is the most recent 303(d) list to be approved by EPA. The 2004 list should be the list used for the purposes of writing discharge permits, watershed characterization, financial assistance funding, TMDL prioritization, and TMDL implementation.
The 1998 Water Quality Assessment (303[d]) list was based on a major change to the segmentation system used to identify impaired waters. In previous lists, whole waterbodies or major sections were listed based on sampling from limited areas within the waterbody. In order to more accurately represent the area of a waterbody that data indicated was impaired, the 1998 segments were limited to the portion of the waterbody located in the same section (township/range/section) as the sample data location.
The Washington Department of Ecology submitted its Candidate 1998 Section 303(d) List to the U.S. Environmental Protection Agency (EPA) on June 29, 1998. On August 26, 1999, Ecology received a partial approval/disapproval letter (PDF) from EPA in response to the list. EPA approved the list that Ecology submitted and proposed adding an additional 130 waterbody/parameter combinations to the list. On January 28, 2000, EPA transmitted their final response to Ecology. As a result of EPA's action, 116 new waterbody/parameter combinations have been added to the list.
The 1998 list includes a total of 643 impaired waterbody segments out of the 1,099 for which we have data, many of which violate standards for more than one pollutant. (The 643 represent only about two percent of all the waters in Washington.) The waterbodies measured were generally those that have a history of pollution. (In 1996 we listed 666 segments representing 611 whole waterbodies. The number of whole waterbodies on the 1998 list increased by 32 over the 611 on the 1996 list).
Bacteria violations account for 285 listings, while temperature affects a total of 282 waters. Dissolved oxygen impairs 133 waterbodies, and pH effects 87 waterbodies. Seventy-eight waterbodies suffer from elevated toxics and 28 have too many nutrients. A total of 38 waterbodies are listed for low flow problems.
Because of public comments, we added 234 waters to the proposed list, based upon new information. We also removed 210 waters because new information showed those waters are now meeting water quality standards, or an adequate management plan has been developed to address the water quality problem.
Water quality data provided to us during the comment period must meet strict requirements. Data collection must follow a documented Quality Assurance/Quality Control plan, and samples must be analyzed at a state-accredited lab.
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