Instream Flows In Washington

Ecology is required by state law to retain adequate amounts of water in streams to protect and preserve instream resources and uses (such as fish, wildlife, recreation, aesthetics, water quality and navigation). One of the best water management tools for protecting stream flows is to set flow levels in regulation. Specific stream flow amounts protected in a regulation are called “instream flows.”

Both the natural environment and our community water supplies rely on healthy stream flows. Yet many streams around the state are often below critical levels. Some streams have dropped to historic lows. Population growth and reduced snowpack continue to put more stress on this finite resource. No new water is being made!

Watershed management groups around the state are examining local water resources and many are working with Ecology to set or revise instream flows in their watersheds. The intent is to set instream flows throughout the state. More information

Setting flows does not put water in streams, and does not affect existing (senior) water rights. Instream flows protect the river from future withdrawals.

	Introduction to Instream Flows and Instream Flow Rules Answers to your basic questions, including: What is an instream flow? Why are stream flows important? What is an instream flow rule? How could setting instream flows affect me?
	The Science Behind Instream Flows How do we determine instream flow levels? We start with fish habitat studies, such as Instream Flow Incremental Methodology (IFIM) and Toe-width.
	Instream Flow Setting Around the State Where can I get more information about my watershed, including whether instream flows have been set?
	Laws and Rules A look at the legal authority to set instream flows by rule and the complex process of developing instream flow/water management rules.
	Resources and Studies Want to know more? Here are links to IFIM studies, publications and other resources.