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Fish Passage

Fish Passage - Overview

Fish Passage Barriers to fish passage, in the form of road culverts, dams, dikes, and other obstructions, reduces the distribution and habitat available to fish, including salmon and steelhead. In particular, the inability of fish to access upstream spawning and rearing areas results in decreased production and in some cases can eliminate fish populations altogether.

Additionally, lack of stream flow, due to surface water withdrawals, also constitutes a significant barrier to fish passage in many locations around Washington. Surface water diversions that are not properly screened to keep juvenile fish out can result in injury and direct mortality to fish

Two of the most vital salmon recovery tools include the correction of human-made fish passage barriers and fish protection through properly screening surface water diversions. During the past two decades, numerous fish passage barriers have been fixed through salmon restoration funds. However, fish barriers are still a big problem and are an important component to restoring salmonid habitat. WDFW estimates that there are still roughly 30,000 barriers statewide to correct.

To be able to explore these barriers, visit this mapping tool developed by USFWS >> Geospatial Fisheries Information Network(GeoFIN)

Fish Screening & Irrigation Diversion Protection

Lambert Creek screen diversion In Washington, stream flows are commonly diverted or pumped to provide irrigation to crops and livestock, which has detrimental effects on fish. There are thousands of in-stream diversions or pumps currently withdrawing water from Washington streams. To adequately protect fish, including salmon and steelhead, from being washed into agricultural fields through irrigation channels or killed through irrigation pumps, fish exclusion devices are necessary. Currently, only a small percentage of stream diversions or pumps are believed to be fully screened to protect fish.

The Fish Screening Technical Assistance unit is an essential part of the state's salmon recovery efforts. This unit is a recognized leader in regional fish protection technologies and has been the primary installer of fish screening facilities in the state. However, unscreened diversions and pumps are so numerous in the state that WDFW cannot tackle the problem without the assistance of landowners, other state and federal agencies, local governments, Indian Tribes, Regional Fisheries Enhancement Groups, Lead Entities, private citizens, and others. For this reason, WDFW has developed guidance documents for the inventory, assessment, and prioritization of poorly screened irrigation diversions and for the design of new structures. WDFW also created a Technical Assistance group to provide statewide assistance with screening project development, conceptual design, screen fabrication design, screen type selection, application of current state and federal screening criteria, and assistance in procuring project funding. For more information , please visit our main website here >> Screening

Design Guidance & Standards

Measuring Culvert
  • Design of Road Culverts for Fish Passage
    Design of Road Culverts for Fish Passage serves as guide for property owners and engineers who are designing permanent road-crossing culverts to facilitate upstream fish migration. It provides guidance for projects involving new culvert construction as well as retrofitting or replacing existing culverts. The designer will need to have a working knowledge of hydraulic engineering, hydrology and soils/structural engineering to accomplish an appropriate design.

  • Road Impounded Wetlands - Planning Guidance
    Road impounded wetlands are the result of undersized or perched culverts in combination with impermeable road fills that create wetland conditions in the upstream impoundment. Often these same culverts block fish and wildlife passage up and down the stream course and interrupt natural channel processes.

  • Evaluation of the Stream Simulation Culvert Design Method in Western Washington
    More than 50 stream simulation culverts have been constructed in Washington State since 1995. This paper summarizes monitoring conducted on 19 of these culverts in various settings.

  • Draft Fishway Guidelines For Washington State
    As part of Washington State's salmon recovery strategy, the Washington State Departments of Fish and Wildlife, Ecology, and Transportation, are currently developing guidelines for salmon habitat protection and restoration. The standards and guidelines are a series of manuals, workshops, and other tools addressing various activities of salmon habitat protection and restoration and are intended to ensure compliance with requirements of the federal Endangered Species Act and state salmon restoration policies.

  • Aquatic Habitat Guidelines
    In 1999, the governor's Salmon Recovery Office commissioned the Departments of Fish and Wildlife (WDFW), Ecology, and Transportation (WSDOT) to develop technical assistance guidance for those who want to protect and restore salmonid habitat. The scope of the program has recently broadened and now includes the promotion, protection, and restoration of fully functioning marine, freshwater, and riparian habitat through comprehensive and effective management of activities affecting Washington's aquatic and riparian ecosystems.

  • For more information, please visit our main website here >> Guidance Standards

Barrier Inventory

Fish Inventory Fish passage inventories lead to identification and assessment of instream features and prioritization of fish passage barriers based on amount, quality, and species utilization of habitat upstream of the barrier.

WDFW Environmental Restoration Fish Passage Program developed criteria to assess and prioritize fish passage barriers throughout the State of Washington. The criteria allows for a consistent set of protocols to determine if a structure is a barrier to fish as well as a prioritization process to correct the worst barriers first. This criterion can be found in the Fish Passage Barrier and Surface Water Diversion Screening Assessment and Prioritization Manual. WDFW's inventory manual is science-based, repeatable, has consistent standards, and is widely used. Additionally, the prioritization allows barriers to be compared between watersheds.

Surface water diversion inventories allow for the identification, assessment, and prioritization of unscreened or inadequately screened diversions in need of correction. Data collected from conducting inventories can be used to plan fish passage barrier correction and screening projects. Funding can later be sought to design and construct the highest priority projects identified.

WDFW has developed and maintains a centralized database, which stores fish passage, diversion screening, fish use, and habitat information resulting from inventory efforts conducted throughout Washington State. The Fish Passage and Diversion Screening Inventory (FPDSI) database can be used to locate, prioritize, select, implement, and monitor fish passage and screening projects. Data from the FPDSI is available online through SalmonScape We encourage all parties assessing culverts to use the WDFW fish passage and screening assessment protocols and share their data to be included in the Statewide database.


Barrier Assessment WDFW collaborates with the Washington State Department of Transportation (WSDOT) to identify and correct barrier culverts under state highways. This 20-year old partnership has resulted in completion of over 245 fish passage projects in Washington streams following detailed fish passage barrier inventories and the standardized prioritization process. These projects have opened up over 820 miles of potential salmonid habitat.
WDFW is partnering with the Washington State Recreation and Conservation Office and the Washington Department of Natural Resources to implement the Family Forest Fish Passage (FFFP) Program. This program is an incentive based program that assists small forest landowners with correcting their fish passage barrier culverts. Since 2003, the FFFPP has opened over 480 miles of stream for salmon to spawn, feed and grow.

Fish passage inventories can be conducted by WDFW staff. Through partnerships, WDFW has recently assisted Washington State Parks as well as local jurisdictions to complete barrier assessments and prioritization efforts.

Lastly, to address fish screening at surface water diversions, WDFW provides technical assistance to private landowners, diversion and irrigation districts, conservation districts, and others, on installing, inspecting, and maintaining screens to keep fish out of pump and gravity diversions. WDFW works with water right holders, water trust organizations, Ecology, and others to restore passage through changes in water use. Many examples include changes in points of diversion.

For additional fish passage information or staff contacts please go here >>Habitat Fish Passage
For more information on
salmon recovery and conservation, please contact
the WDFW Fish Program.

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