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 water bodies are polluted, and decide if further action is needed. This policy also explains data submittal, and the data quality necessary for inclusion in the water quality assessment. The policy is comprised of two chapters:

Chapter 1: Assessment of Water Quality for the Clean Water Act Sections 303(d) and 305(b) Integrated Report

Chapter 1 describes how water body segments are assessed to determine attainment with WAC 173-201A (surface water quality standards) and WAC 173-204 (sediment management standards). After undergoing assessment, the segments are placed in various assessment categories. These categories identify the status of the water and denote future regulatory and restoration actions to bring the water back into compliance with the standards .

The chapter also provides specifications for data submittal and data quality necessary for inclusion in the assessment. This chapter — in combination with the guidance documents referenced therein — constitute the “Listing Methodology” for the Integrated Report required by the U.S. Environmental Protection Agency, which is considered to be 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. Agency actions include:

  1. Determinations of whether a surface water is supporting its designated use, such as the 303(d) and 305(b) assessment processes.
  2. Establishment of a total maximum daily load (TMDL) and the associated load allocations and wasteload allocations.
  3. Revisions to the water quality standards.