In 2020, WSDOT received a Salmon Recovery Funding Board (SRFB) grant to explore a floodplain restoration alternative as a potential solution to reduce flood and erosion damage to State Route 20 during Skagit River floods and improve native fish habitat in the river and its floodplain.
The study team began their work in January 2022, documented existing floodplain processes and habitat conditions in the watershed, and presented them to stakeholders and community members during a virtual community workshop in November 2022. The team also asked for input on the evaluation criteria that will be used to evaluate potential floodplain restoration alternatives and updated these criteria based on feedback received during the workshop.
Currently, the study team is reviewing the seven existing small side channels they identified to determine their potential for enhancement and will eliminate those that do not meet the evaluation criteria. To develop alternatives, the team will apply a hydraulic model to several combinations of these potential flow-paths to predict expected future conditions. They will then apply the evaluation criteria to the two best alternatives and compare them to the no-action alternative.
We will present the results of the analysis and seek input on a feasible alternative concept during our final virtual stakeholder meeting on June 1 from 5:30 to 7:30. To participate in the virtual SR 20 Skagit O’Brian Reach Community Workshop #2, please register using the link at the bottom of this webpage.
January 2022 - December 2023
The SR 20 Skagit River O’Brian Reach Feasibility Study area is located along SR 20 near Rockport at milepost 101. The purpose of the study is to assess floodplain connectivity and channel processes to determine if there is a feasible floodplain restoration action that:
Reduces erosion and flood damage to SR 20 during frequent flood events, which often result in the need for emergency repairs and highway closures.
Improves degraded fish habitat in the Skagit River and its floodplain by enhancing the connectivity of floodplain habitats to the river during small and medium-sized floods.
Is acceptable to adjacent landowners and stakeholders.
The intent of the feasibility study is to explore an integrative and collaborative approach to addressing a recurring highway problem in a river basin with a great deal of conservation interest. The primary objectives of the study include:
Engage early with stakeholders and potential future project partners.
Understand habitat conditions and floodplain processes in the O’Brian Reach and factors that cause bank erosion and flooding.
Develop several alternatives that enhance floodplain connectivity, distribute flows more broadly across the floodplain, reduce the force of high river flows on the highway embankment, and improve habitat for native salmon and steelhead.
Select a feasible alternative and develop a project concept with input from stakeholders in the basin.
Document the results in a feasibility study report.
SR 20 near milepost 101 has experienced frequent embankment erosion and flooding and has required repeated emergency repairs from flood events in the Skagit River. This section of the highway is located below the 10-year flood elevation along a meander of the Skagit River that has been slowly migrating downstream.
For several thousand years, the Skagit River migrated freely across the valley creating an extensive network of sloughs, wetlands, ponds, side channels and other off-channel habitats vital to salmon and other native species. Historic changes to the river altered the natural processes that maintain these floodplain habitats and their connection to the river. The loss of native salmon habitat and impairment of natural processes are major factors in the decline of Chinook, chum, coho and pink salmon, steelhead, bull trout and resident trout in the Skagit River.
Improving salmon and steelhead habitat within Washington’s rivers has become a top priority for public agencies, tribes and private conservation groups, including in the Skagit River.
In November 2017, a small (10-year) flood event in the Skagit River eroded the embankment and destroyed the eastbound lane of SR 20, requiring a two-week closure to rebuild the highway and install emergency bank protection. Although this work was necessary, the large rock typically used in these repairs contributes to degraded fish habitat in the Skagit River. WSDOT has conducted similar repairs to this section of SR 20 many times since 2004, and again in November 2021. Historic damage to this highway is often associated with these smaller, frequent flood events.
WSDOT’s Chronic Environmental Deficiencies (CED) program has been working on a solution to the erosion and flooding problem. The purpose of the CED Program is to proactively implement long-term, nature-based, fish-friendly retrofits at frequent repair sites along WSDOT’s river-adjacent highways. These aim to work with watershed processes that often occur on a large scale.
A large portion of the floodplain of the O’Brian Reach is undeveloped, already dedicated to conservation use and managed by organizations working toward salmon recovery in the basin. This presented an opportunity to collaborate with potential conservation partners on a large-scale approach that addresses both problems, instead of implementing a site-specific solution adjacent to the highway.
Maximizing the value of cooperative partnerships:
In cooperation with our partners and potential partners this study will:
Provide an engagement process and information to identify and evaluate feasible floodplain restoration alternatives that address the habitat degradation, scour, and flooding problems. These may include enhancing and reconnecting existing side channels or restoring functional channel patterns on the existing floodplain.
Evaluate if floodplain enhancement alternatives that distribute Skagit river flow more broadly across its floodplain would reduce the flooding and scouring flows at the highway embankment.
Evaluate whether these alternatives would increase and diversify rearing habitats by creating shallow stream margins, side channels, and other slow-moving habitats that could benefit juvenile life history phases of almost all species of salmonids.
Engage people and provide opportunities for input on evaluation criteria, potential alternatives, and selection of a feasible alternative, so that the solution is palatable and could result in implementation of a future project.
Contribute to reducing flooding of other river-adjacent properties and infrastructure.
View the workshop notes (PDF 355KB) and presentation (PDF 22MB) from Community Workshop #1. Participants in the November 2022 workshop learned about the study goals, results of the existing floodplain processes and habitat conditions assessment and provided input on the evaluation criteria.
Attend Virtual Community Workshop #2
Attend our second community workshop on Thursday June 1, from 5:30 to 7:30 p.m. The purpose of the workshop is to:
Provide an overview and update of the SR 20 Skagit O’Brian Reach Feasibility Study.
Present the results of the alternatives analysis.
Seek input on a feasible alternative concept to inform the results of the final study report.
Or attend the Zoom videoconference streamed at the Upper Skagit Library, 45952 Main St. in Concrete. WSDOT staff will help attendees participate in the online meeting.
To attend at the library, please RSVP by Sunday May 21. Email firstname.lastname@example.org with the subject line "Register in person for O’Brian Reach Workshop" or leave us a voicemail at 360-705-7488 with your name, phone number, and number of in-person attendees. We will confirm final details by May 25.
Study existing conditions using the hydraulic model.
Stakeholder meeting #1: Present results of existing conditions analysis and solicit input on potential project alternatives.
Stakeholder meeting #1: Present results of existing conditions analysis and solicit input on potential project alternatives and evaluation criteria.
Refine evaluation criteria based on community input.
January – June 2023
Develop practical alternatives based on evaluation criteria, community input and data analysis.
Evaluate two potential alternatives using the hydraulic model and evaluation criteria.
Compare alternatives to existing conditions.
Review and revise modeling results.
Stakeholder meeting #2: Present the alternatives and solicit input on a feasible alternative concept.
July 2023 – December 2023
Incorporate feedback and refine the analysis.
Select feasible project concept.
Prepare draft report.
Stakeholders review the draft report.
Finalize Skagit O’Brian Reach Feasibility Study Report.
Final study report published.
The SR 20 Skagit O’Brian Reach Feasibility study is sponsored through WSDOT’s Chronic Environmental Deficiencies (CED) program and funded with a salmon recovery grant and contributions from partners in the following amounts:
Funding has not yet been identified for the design or construction of a project.
This study is currently in progress. The SR 20 Skagit CED O’Brian Reach study will identify river processes that contribute to erosion and flooding of SR 20 and recommend a project concept that reduces flooding of the highway and improves fish habitat within this section of the Skagit River.
The outcome will be a report describing existing conditions, river processes, evaluated floodplain restoration alternatives and a feasible project concept. The report is expected to be available in December 2023.
Natural Systems Design (NSD) is WSDOT’s lead contractor implementing the study, with assistance from Veda Environmental leading the stakeholder engagement and Natural Waters LLC for quality control and quality assurance.