Washington State's Water Quality Assessment [303(d)]

Washington State Department of Ecology

Ecology home > Water Quality > WQ Assessments [303(d)] > Final 2004 Submittal > Water Quality Listings by Category

Water Quality Listings by Category

The 2004 list is available for informational and reference use only.

Use the most recent 303(d) list to be approved by EPA for the purposes of writing discharge permits, watershed characterization, financial assistance funding, TMDL prioritization, and TMDL implementation.

The 2004 list divided water bodies into one of five categories:

Category 5: Polluted waters that require a TMDL. Placement in this category means that Ecology has data showing that the water quality standards have been violated for one or more pollutants, and there is no TMDL or pollution control plan. TMDLs are required for the water bodies in this category.
1. Overview (PDF) of the Category 5 List
2. Temperature listings for fresh water
  1. Overview of temperature criteria issue (PDF)
  2. Regional temperature listings (PDF)
Category 4: Polluted waters that do not require a TMDL is for waters that have pollution problems that are being solved in one of three ways.
- Category 4a is for water bodies that have an approved TMDL.
  1. Overview of the Category 4A list (PDF)
  2. List of Water Quality Improvement Plans (TMDLs) in Washington State
- Category 4b has is for water bodies that have a pollution control plan in place. While pollution control plans are not TMDLs, they must have many of the same features and there must be some legal or financial guarantee that they will be implemented.
  1. Overview of the Category 4B list (PDF)
- Category 4c is for water bodies that are impaired by a non-pollutant. These impairments include low water flow, stream channelization, and dams. These problems require complex solutions to help restore streams to more natural conditions.
  1. Overview of the Category 4C list (PDF)
Category 2 is for waters of concern. There are several reasons why a water body would be placed in this category. A water body might have pollution levels that are not quite high enough to violate the water quality standards, or there may not have been enough violations to categorize it as impaired according to Ecology’s listing policy. There might be data showing water quality violations, but the data were not collected using proper scientific methods. In all of these situations, these are waters that we will want to continue to test.
1. Overview of the Category 2 list (PDF)
Category 1: Meets tested standards is for clean waters. Placement in this category does not necessarily mean that a water body is free of all pollutants. Most water quality monitoring is designed to detect a specific array of pollutants, so placement in this category means that the water body met standards for all the pollutants for which it was tested. Specific information about the monitoring results may be found in the individual listings.
1. Overview of the Category 1 list (PDF)
Waterbody segments that moved off of the 1998 303(d) List (PDF):

Why were some streams listed in more than one category?

A single water body segment may be listed multiple times, depending on how many tested pollutants violated the water quality standards. For example, a water body may have been tested for a group of pollutants might be listed in category 5 because temperatures consistently violated standards; in category 2 because some high bacteria counts were found, but not enough to list it as impaired; and in category 1 because dissolved oxygen levels were good. Each listing will also include the medium in which the pollutant was measured—water, sediment, or tissues.

Back to 2002/2004 303(d) List Home Page

Last updated February 2009