Integrating Climate Change into Culvert Design

Full Title

An Applied Case Study to Integrate Climate Change into Design and Permitting of Water Crossing Structures

Project Overview

The Washington Department of Fish and Wildlife (WDFW) not only designs fish passable structures, but also permits and provides technical guidance to hundreds of others entities annually, specifying how to build and install fish passable water crossing structures. Despite WDFW’s understanding of potential climate change implications for water crossing design, WDFW has been unable to convert projected climate-induced hydrological changes into water crossing design guidance and permitting decisions.

This project addresses two important problems:

  1. Current design standards used by WDFW do not consider future changes in hydrology, despite water crossing project lifespans of 30 – 100 years, and
  2. Climate projection metrics (e.g., changes in flood frequency and basin hydrology) do not directly translate into the metrics (e.g., bankfull width and sediment gradations) used by WDFW and other engineers for water crossing design.

This project will map WDFW’s culvert design and permitting decision process and identify decision elements potentially sensitive to climatic changes and impacts. We will then translate existing projections of hydroclimatic data into metrics used by engineers for these decisions and work to incorporate these data into water crossing design guidance and permitting decisions.

This project will allow WDFW to design and permit prioritized water crossings that are resilient to future projected hydrologic changes, ensuring continued habitat connectivity and other benefits for the expected life of the structure by incorporating projected changes in stream hydrology into design and risk assessment.

Project results will be well timed; the number of fish passage barriers replaced annually is expected to increase dramatically in response to a 2013 federal court injunction directing Washington State to repair all culverts that block 200 meters or more of salmon habitat, and many of those replacements occurring by 2016. Effectively tackling this mandate requires that both prioritization of culverts for corrective action and design of the water crossing structures replacing those culverts be done in a climate-informed fashion.

Key Personnel

* Indicates CIG Personnel or CIG Affiliate(s)

  • Timothy Quinn (Principal Investigator), Washington Department of Fish and Wildlife
  • Lynn Helbrecht, Washington Department of Fish and Wildlife
  • Donald Ponder, Washington Department of Fish and Wildlife
  • Jennie Hoffman, Climate Adaptation Research
  • Ingrid Tohver, University of Washington*
  • Guillaume Mauger, University of Washington*

Key Collaborators

Dan Siemann, Washington Department of Natural Resources; Carol Lee Roalkvam, Washington State Department of Transportation; Jason Dunham, U.S. Geological Survey; Bill Shelmerdine, U.S. Forest Service; Dave Peterson, U.S. Forest Service

Funder(s)

North Pacific Landscape Conservation Cooperative (NPLCC)

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