Chapter 173-201A WAC

Water Quality Standards for Protecting Human Health and Updated Tools to Implement the Standards


We recently updated our agency's web pages.  If you are having trouble finding specific information or documents related to this rulemaking, please contact:

Becca Conklin


On August 1, 2016, we adopted a rule that updates surface water quality standards to include human health criteria and updated tools to implement the standards.

This rule retained the cancer risk rate (10-6) and is in keeping with the governor's directive from October 2015. It aims to protect the health of Washington’s people, fish and the economy. This work is accompanied by longstanding and continued efforts to reduce toxic threats in Washington.

EPA's decision on our adopted rule

On November 15, 2016, the US Environmental Protection Agency (EPA) made a decision on Washington state’s surface water quality standards, Chapter 173-201A WAC. The decision included a partial approval and partial disapproval of our standards.

Process of development

Ecology’s process for developing these rule amendments included consulting with tribes, outreach to affected stakeholders and the public, and following formal steps for rule adoption. Review the rulemaking documents, timeline,  and public involvement details using the links below.