Water quality assessment Policy 1-11
Water Quality Policy 1-11 is the guiding policy that we use to assess water quality data, determine if waterbodies are polluted, and decide if further action is needed. This policy also explains how to submit data and describes the data quality necessary for inclusion in the water quality assessment.
The policy is comprised of two chapters:
Chapter 1: Washington’s Water Quality Assessment listing methodology to meet Clean Water Act requirements
Chapter 1 describes how water body segments are assessed to determine if they meet surface water quality standards (WAC 173-201A) and sediment management standards (WAC 173-204). After undergoing assessment, the segments are placed in assessment categories. These categories identify the status of the water and determine future regulatory and restoration actions to bring the water back into compliance with the standards.
The chapter also provides specifications for submitting data and data quality necessary for inclusion in the assessment. This chapter — in combination with the guidance documents referenced there — constitute the “Listing Methodology” for the integrated report required by the U.S. Environmental Protection Agency (EPA), which serves as the Section 303(d) list and 305(b) report as required by the federal Clean Water Act.
Chapter 2: Ensuring credible data for water quality management
Chapter 2 describes the quality assurance measures, guidance, regulations, and existing policies that help ensure the credibility of data and other information used in agency actions on state surface water quality. This chapter meets the requirements of Washington's 2004 Credible Data Act.
Agency actions include:
- Determining whether a surface water body is supporting its designated use, such as the 303(d) and 305(b) assessment processes.
- Establishment of a water cleanup plan, or TMDL (for total maximum daily load), and the associated load allocations and wasteload allocations.
- Revisions to the water quality standards.
In March 2023, we finalized the 2022 revisions of Policy 1-11, Chapter 1: Washington’s Water Quality Assessment Listing Methodology to Meet Clean Water Act Requirements.
The revision included:
- A new freshwater harmful algae blooms (HABs) methodology to identify waterbodies where HABs are impairing recreational uses.
- Non-substantial edits to provide improved clarity to the policy, mainly around Section 1E on information submittals based on narrative standards. This also included a note on the temporary suspension of the natural-conditions methodology.
The 2022 revisions were incorporated into an updated, accessible template. While the cover page and document may look new, no changes were made to the policy outside of the 2022 revisions.
We held a 60-day public review and comment period, and an informational webinar, to discuss the revisions. The comments and response can be accessed below.
Major revisions to water quality Policy 1-11, Chapter 1 were completed in 2018. Further revisions in 2020 updated assessment methodologies for changes to the recreation use bacteria criteria.
Water Quality Policy 1-11, Chapter 2 was published in 2006 then updated for accessibility in 2021.
We review the policy as the first step in the process to update the assessment.