Instream Flow Laws and Rules

Instream flow rules recently adopted or under development

Authority for Setting Flows

Authority for setting flows is derived from state statutes.  The primary statutes relating to flows and flow setting are:

Primary Statutes and Legal Basis Relating to Instream Flows (24kb pdf)

Rule making for flows is done through Ecology’s rule-making authority in the Administrative Procedure Act Chapter 34.05 RCW.

When stream flows are set in rule, the effective date (also called a "priority date") is thirty days after the date of rule adoption.  An instream flow is, in essence, a water right for fish and other instream resources. While an instream flow does not affect existing water rights, water rights issued after the rule adoption are junior to the instream flow, and can only be exercised when the instream flow is being met.