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Streamflow Restoration

Establishing adequate instream flows—essentially a water right granted to the river itself—is one of the best legal tools we have to ensure sustainable water management and build climate resiliency.

Photo: Bill Truslow

Understanding Instream Flows

Sound science is vital to the management of natural resources, especially when managing water. An instream flow is used to identify the rate of water flow, measured in cubic feet per second (cfs), required at different times of the year at a specific location in a waterway. Instream flows protect the river from new withdrawals that would threaten the availability of water needed to ensure healthy aquatic habitats to sustain wildlife, provide excellent recreational opportunities, and support agriculture and domestic uses.

Seasonal changes cause natural stream flows to vary throughout the year, so instream flows usually vary from month to month rather than one flow rate year-round. Once instream flows are set, when actual streamflows drop below the adopted instream flow levels, junior water rights (those established after the instream flow) can be temporarily curtailed to keep the water in the stream. For all intents and purposes, an instream flow is essentially a water right granted to the river itself.

Establishing this base protection helps guarantee the longevity of our water resources and provides assurance that they will continue to bolster our economy and keep Washington uniquely beautiful indefinitely. The Center for Environmental Law and Policy is currently working towards adoption of instream flows in Southwest Washington.

Fish-Flows Determine Instream Flow

When deciding what flow levels to protect, much of the discussion centers on fish needs. There are several state laws that specifically call for protecting fish, establishing legal requirements and precedent to support the Department of Ecology’s authority to establish instream flows. Furthermore, it is often the case that if the fish are doing well, then other instream resources are too, and fish needs are often easier to measure than some other instream values.

Fish-flow studies utilize a variety of methodologies to understand how natural/historic levels have been altered and to what extent this change negatively affects the timing and quality of water flow as well as temperature patterns. The data is compiled to inform water managers about the flows needed for fish rearing, spawning, and/or migration and overall habitat suitability for both juveniles and adults. Once fish biologists have determined which seasonal flow levels in a stream provide the best fish habitat, other considerations are then brought into the discussion among local agencies, NGOs, tribes, stakeholders, and the public.

Photo: © Jason Ching


Due to a long history of shifting policies, impactful court decisions, and various watershed management proposals, there is often confusion regarding individual water rights and instream flows. Below are the answers to some common questions.

Q: How will my existing water right be affected once an instream flow rule is adopted?

A: It won’t. An instream flow is junior to any pre-existing water rights and can’t affect them. Even if the flow is not being met, water rights that predate the flow rule may use water. In fact, instream flows protect existing water rights because they ensure that the river won’t be further over-allocated.

Q: How will an instream flow affect my permit-exempt well?

A: It won’t. Like existing water rights, permit exempt wells that are in use before an instream flow rule is adopted are senior to the instream flow and immune from curtailment to protect that instream flow.

Q: Once the instream flow rule is adopted, does that mean no new water will ever be given out?

A: No. Establishing instream flows does not mean there is no opportunity to obtain new water rights for projects proposed after the flow rule. Interruptible water rights that are usable whenever flow levels exceed the instream flow can still be issued. There is also always the option to obtain a water right by mitigating use to avoid impacts on the instream flow.

Legal Precedent

Where We Are Today

Instream flows have been set in about half of Washington’s 62 watersheds, but all those in orange desperately need updating. CELP is working to ensure all of our waterways gain this valuable, legal protection based on the best-available, up-to-date science.

Perhaps our ancestors, our fathers, we ourselves not too long ago were willing to throw away as worthless some scenic, recreational, and environmental factors. Perhaps they were regarded as worthless because of their abundance, but now we realize what is left is far from abundant, that it is scarce, partly because we have already thrown away so much, partly because there are now so many of us that we compete with each other for what is left, and partly because the opportunities for enjoyment have been broadened by the automobile and highway. The law is a mechanism for getting things done, for accomplishing the purposes of society, for requiring some things and forbidding others. If the people of the United States or of a state desire to keep water in a stream or to put it back in a stream a law can be framed that will do the job.

Frank J. Trelease, Dean Emeritus University of Wyoming College of Law

CELP’s Work

Argued Case to Uphold Dungeness River Instream Flow Rule

In October 2016, Thurston County Superior Court Judge Gary Tabor upheld the Instream Flow Rule for the Dungeness River basin, denying a challenge from a group of property owners and developers. CELP Staff Attorney Dan Von Seggern intervened to defend the Rule, arguing the case alongside Ecology’s attorneys. After the decision, he stated: “This is a win for the environment and for water management in Washington. The Dungeness Rule strikes a balance by protecting streamflows, fish, and senior water users, while still providing water for responsible development. CELP is pleased with Judge Tabor’s decision and hope that this Rule will provide a guide to protecting other rivers in our state.”

In upholding the Rule, Judge Tabor held that the Rule was not unlawful and that Ecology did not exceed its authority when it adopted the Rule. He also reaffirmed that permit-exempt wells are subject to the “first-in-time” system of water appropriations used in Washington.


Legal Support Leads to 'Swinomish Decision' Preserving Skagit River Instream Flow

Along with partner Earthjustice, CELP filed a friend of the court brief with the Washington State Court of Appeals in support of the Swinomish Indian Tribal Community and its ongoing effort to protect the Skagit River and salmon. In the brief, Earthjustice and CELP argued that Ecology cannot allow more water to be withdrawn from the troubled Skagit River and its tributaries for new junior water uses because such new uses would further impair stream-flows.

Ultimately, the State Supreme Court ruled in favor of the Swinomish Tribe in 2013.

“This decision is a huge victory for Swinomish, for salmon and for the water that salmon need to survive,” said Swinomish Chairman Brian Cladoosby. “Ecology had a choice to do the right thing or the wrong thing in 2006, and unfortunately, it chose to do the wrong thing. The court’s decision vindicates the tribe’s position and confirms that Ecology cannot make an ‘end run’ around laws that protect instream flows for fish.”



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