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Instream Water Rights (ISWRs) – Frequently Asked Questions

Q: What are instream water rights (ISWRs)?

A: Instream water right – a water right held in trust by the Oregon Water Resources Department for the benefit of the people of the state of Oregon to maintain water instream for public use. An instream water right does not require a diversion or any other means of control over the water. (ORS 537.332(3)).

Q: Why are ISWRs needed?

A: Oregon’s Water Code, established in 1909, created a system of water allocation and distribution that did not consider water for instream uses, leading to degradation of Oregon’s freshwater resources. Over time, it became clear that a legal system was needed to protect flows in support of ecological uses and minimizing pollution. Although the 1955 Minimum Perennial Streamflow Act established monthly minimum flows for fish and water quality through administrative rule, these flow recommendations were not legally protected and could be disregarded during times of shortage. In response to these shortcomings, the 1987 Instream Water Right Act officially recognized instream flows as a beneficial use, giving them the same legal status as consumptive water rights (ORS 537.350). Implementation of the ISWR Act is a means of achieving a more equitable allocation of water in a system where the values of instream flows were not initially recognized.

ISWRs are the state’s mechanism to provide water for fish needs and healthy ecosystems that support multiple public uses (e.g., recreation, fishing, tourism). ISWRs help achieve Oregon’s Integrated Water Resources Strategy (2012, 2017) instream goals for protecting the full suite of flows for fish and wildlife, water quality, recreation, scenic attraction, and supporting cultural values and healthy economies.

Q: How are ISWRs established?

A: ISWRs may be established in three ways:
1) Conversion of minimum perennial streamflows to instream water rights (ORS 537.346);
2) Temporary lease, time-limited transfer, or permanent transfer of water rights established for other uses (ORS 537.348);
3) Request by state agencies. Three state agencies – the Oregon Department of Environmental Quality, Oregon Parks and Recreation Department, and the Oregon Department of Fish and Wildlife – are authorized to request instream water rights in the amount needed to support recommended public uses (ORS 537.336).

Q:  How does an ISWR affect an existing water right?

A: Like all other water rights, ISWRs are based on the doctrine of prior appropriation. Instream water rights do not take away or impair any existing water right with an earlier priority date (ORS 537.334). The priority date for a new ISWR is the date that the application is submitted to the Water Resources Department (ORS 537.341), and ISWRs are often quite junior compared to existing out-of-stream uses. The earliest ISWRs, which are converted minimum perennial streamflows, have priority dates starting in the late 1950s; ISWRs requested by state agency application have priority dates from the 1980s and later. ISWRs established through conversion, purchase, lease, or gift retain the original priority date associated with the water right (ORS 537.346 and ORS 537.348).

Q: Why are ISWRs approved for amounts greater than what WRD estimates is available?

A: The amount of appropriation for out-of-stream uses is not a factor in determining an instream water right (OAR 690-077-0015). Instream allocations are based on natural streamflowthe amount of water that would be expected if no water was withdrawn for out-of-stream uses. Even in an over-allocated basin – which indicates that requested ISWR flows are unlikely to result in additional instream water in many years – ISWRs are important because they provide a goal for achieving the instream flows needed to support identified public uses. Setting biological flow targets helps guide agencies and other collaborators in voluntary restoration efforts and long-term basin planning.

Q: Why does ODFW apply for ISWRs on reaches that already have an existing ISWR?

A: In 2012, Oregon’s Integrated Water Resources Strategy was developed by a broad group of stakeholders and incorporated public input gathered through meetings and comments. First adopted by the Oregon Water Resources Commission in 2012 and updated in 2017, it provides a blueprint for meeting the state’s in and out-of-stream water needs now and into the future, when water availability and use will be impacted by climate change. In the suite of recommended actions, ODFW was specifically directed to determine flows needed to support instream needs and to establish additional ISWRs to protect flows. ODFW has re-initiated the instream filing process as directed in the Integrated Water Resources Strategy, and new data and updated analyses indicate that some existing ISWRs are not sufficient to protect public uses served by the ISWRs (conservation, maintenance and enhancement of aquatic and fish life, wildlife, and fish and wildlife habitat).

Q: How does ODFW determine flow amounts and reach length when applying for ISWRs?

A: It is ODFW’s policy to apply for ISWRs on waterways exhibiting fish and wildlife values (OAR 635-400-0005). ODFW’s ISWR rules dictate the methods that can be used to apply for an ISWR (OAR 635-400-0015). Instream flow recommendations used in ISWR applications must be derived from field-based studies, augmented with measured or modeled estimates of naturally available flow. Flows must be based on habitat criteria. To estimate fish habitat available over a range of discharges, hydrologic and habitat data are collected over a range of flows (e.g., low, medium, and high). Habitat preferences vary for different species of fish and for each of their life stages. Species-specific flow targets are then placed within a framework of naturally-occurring flows based on long-term hydrologic records to determine the requested flow amount. Instream flow targets and resulting ISWRs are applicable over lengths of stream with relatively uniform biological and hydrologic conditions. Significant changes in hydrologic (e.g., tributary inputs) or biologic (i.e., species distribution changes) conditions upstream and downstream from the instream flow study reach define reach breaks. 

Q:  Are water right transfers allowed on reaches with existing ISWRs?

A: Proposed changes to a water right cannot injure other existing water rights, including ISWRs. If OWRD determines a change in point of diversion would injure an ISWR, they may only consent to the change upon a recommendation from the agency that requested the ISWR as required by statute (ORS 540.530). ODFW makes a recommendation to OWRD to consent to injury of ISWRs for aquatic life when there is a net benefit to the resource consistent with the purposes of the ISWR. Through the statutory Consent to Injury process, ODFW works with landowners in meeting their water needs while avoiding or minimizing impacts to the instream water right and/or fish and wildlife habitat. Mitigation consistent with ODFW’s Fish and Wildlife Habitat Mitigation Policy (OAR 635-415) is sometimes required to offset the transfer’s impact, and ODFW assists landowners in developing an appropriate Mitigation Plan when possible.


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