Chehalis Basin Strategy
Taking action to reduce major flood-related damage and restore aquatic species habitat in the Chehalis River Basin
The Chehalis River Basin
Washington’s Chehalis River Basin is a unique mosaic of distinct communities—commercial and recreational fishers, farmers, foresters, and many more. What we call the Chehalis Basin today makes up the ancestral lands of numerous tribes. Two sovereign nations exist within the Basin—the Confederated Tribes of the Chehalis Reservation, and the Quinault Indian Nation which has treaty rights to fish, hunt and gather in the Chehalis Basin. Both the Quinault and the Chehalis people are inseparably linked with the watershed, where they have stewarded salmon, steelhead, and other species and the habitat upon which they depend for thousands of years.
The state’s second largest river drainage system is made up of a variety of distinct landscapes including mountain foothills, commercial farms and forests, and small towns and cities. Important and rare species of fish and aquatic wildlife live in its wetlands, streams, and rivers.
Flooding has always been present in the Basin but with climate change, disaster is no longer an isolated incident. Decades of intensive land use have stretched the capability of lands and waterways to absorb even normal levels of flooding. This puts homes, businesses, towns, and fish and wildlife at greater risk.
The Chehalis Basin Strategy is an ambitious collection of near- and long-term actions as well as small- and large-scale projects designed to bring people together to achieve a two-pronged objective: Restore aquatic species habitat and reduce major flood-related damage to communities and landscapes.
The Chehalis Basin is a 2,700 square-mile river drainage system located in southwest Washington along the Chehalis River and its tributaries. It is the second-largest river basin in Washington, flowing from the Willapa Hills and the hills east of Chehalis and Centralia, past the Capitol State Forest and Olympic Mountains into Grays Harbor.
Flood Damage Reduction
Due to its wide, flat topography, flooding has always been present in the Chehalis River Basin. The 125-mile mainstem of the Chehalis River flows into Grays Harbor estuary on the Pacific Coast. Besides the Chehalis River, the 2,700 square-mile drainage basin also includes the Black, Elk, Hoquiam, Humptulips, Johns, Newaukum, Satsop, Skookumchuck, Wishkah, and Wynoochee rivers and their tributary streams.
As the climate changes, catastrophic floods in the Basin are no longer an isolated incident. Since 1971, there have been 12 declared flood emergencies in the Basin, and 100-year floods are occurring with greater frequency. In fact, six of the Basin’s largest historical floods have happened during the last 30 years. In 1996, 2007, 2009, and 2022, the cities of Chehalis and Centralia experienced major flooding causing millions of dollars in property damage. On several occasions, floodwaters also closed U.S. Interstate 5 – the north-south thoroughfare linking Seattle and Portland, Ore. – as well as rail lines and other area highways.
Flood years in the Chehalis River Basin
Extreme flood event in Centralia-Chehalis area (left). Kayakers paddle the flood waters covering Interstate 5 (right)
The Chehalis Basin Strategy is designed to help communities and landowners prepare for flooding by reducing or preventing the environmental, economic, and cultural harm major floods can cause. The Strategy is helping prepare the region for increases in the frequency and severity of future flooding through local and large-scale flood damage reduction actions. Many of these actions also support habitat restoration for salmon and other fish and wildlife species.
Between 2017 and 2022, the state has invested $48.4 million to complete 39 flood damage reduction projects in the Basin.
Explore the flood damage reduction projects below
Take a look at three projects in more detail below...
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Montesano Wastewater Treatment Plant
Montesano, Wash., is located about 40 miles southwest of Olympia. The city’s wastewater treatment plant is located along the banks of the Wynoochee River in the Chehalis Basin. The river bank had been eroding at the rate of 17 feet per year, threatening to breach the plant and potentially send millions of gallons of raw sewage down the Wynoochee to the Chehalis River and Grays Harbor.
Montesano worked on a multi-phased solution using log jacks, large structures made up of tree trunks and large boulders that slow water and mimic some aquatic habitat. In 2018, a series of log jacks were constructed on the river bank above the water line. As the bank continued to erode, the log jacks fell into the Wynoochee River, reducing erosion while buying time to develop a permanent solution.
The second phase of the project in 2019 involved placing log jacks in the river adjacent to the treatment plant’s sheetpile wall. The permanently-placed log jacks are already creating a noticeable change to the flow path of the river. It is anticipated the log jacks will ultimately help protect and improve the quality and quantity of important fish habitat as well as create additional channel complexity.
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China Creek
The City of Centralia’s China Creek Phase 1 and Phase 2 projects serve as a model for fish habitat enhancement and flood damage reduction opportunities. China Creek originates east of Centralia and flows through the heart of the city. In the past, the creek flowed into the Skookumchuck River. Today, the creek flows through concrete box culverts under city streets and under U.S. Interstate 5 before joining the Chehalis River.
China Creek is prone to local flooding from small, high intensity storms. However, it is not usually a source of major flooding by itself. During the catastrophic storms and floods that hit the Chehalis River Basin every five to 10 years, China Creek floods businesses, homes, and streets in Centralia.
In 2019, the City of Centralia, with funding from the Chehalis Basin Flood Authority, completed China Creek Phase 1 to reduce flood damage, open China Creek to fish passage, and create better salmon spawning habitat and more storage in its upper reaches. That project increased stormwater storage upstream, reducing the level of floodwater in Centralia during high flows. The project also included planting trees along the banks of the creek, creating a more complex channel and other important aquatic habitat for fish and other species.
The China Creek Phase 2 project also reduces flood damage, opens China Creek to fish passage, creates better salmon spawning habitat and increases stormwater storage through the installation of a flow control structure. The flow control structure was designed with a 100-year flood event in mind. Although the structure does not have the capacity to contain a 100-year flood event, the structure is designed to increase the time China Creek flows are concentrated downtown so they do not coincide with peak discharge time for other outfall flows.
The Phase 2 project was made possible by a land donation from Sun Beach Properties. The Agnew Mill Pond property makes up a large portion of the China Creek Phase 2 area which includes a 0.9-mile walking trail. The China Creek Phase 2 project was completed in early 2022 with funding from the Chehalis Basin Flood Authority. Together, the projects aim to enhance fish habitat and reduce flood damage in Centralia.
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Aberdeen-Hoquiam Flood Protection Project
The cities of Aberdeen and Hoquiam are located close to where the mainstem of the Chehalis River empties to the marine waters of Grays Harbor. The cities are working together on coordinated approach to reduce flooding, promote community development, and support salmon recovery efforts. The cities are working to invest $94 million to design and construct the Aberdeen-Hoquiam Flood Protection Project. The Chehalis Basin Strategy has so far provided $18 million toward the flood mitigation project. The cities also secured a $50 million federal grant for the project.
Slated to be completed in four phases, the flood mitigation project is made up of the North Shore Levee and North Shore Levee – West Segment. Once constructed, the 10.9 miles of levees will benefit Aberdeen and Hoquiam by protecting more than 3,100 properties and 994 businesses from flooding, creating and maintaining 842 jobs, and significantly reducing the economic burden of flooding on the community.
Hoquiam and Aberdeen are located in Grays Harbor County, one of the most economically disadvantaged communities in Washington. Once the levees are built, property owners and businesses will save $1.2 million annually in required Federal Emergency Management Agency flood insurance premiums. The cities are working to get the project ready for construction by July 2023.
Aquatic Species Restoration
The Chehalis River Basin is home to abundant wildlife. It is one of the few major river basins in Washington without any federally-listed endangered salmon and has the highest diversity of amphibian species anywhere in the state. The Basin supports various fish species including salmon, steelhead trout, lamprey, and the Olympic mudminnow.
However, the Basin’s ability to sustain some types of fish has been greatly diminished. Poor returns of migrating fish populations have significantly limited harvests for Tribal and non-tribal fisheries. If aquatic habitat in the Basin does not improve, salmon and steelhead could become endangered, along with other important species.
The Aquatic Species Restoration Plan is a key component of the Chehalis Basin Strategy. It’s a science-based plan designed to help restore aquatic species habitat and enhance local economies. It was designed to efficiently and effectively rebuild and protect a productive ecosystem that is able to bounce back in the face of climate change impacts.
Between 2017 and 2022, we have invested $50.4 million to complete 68 aquatic species restoration projects in the Basin.
Explore all aquatic species habitat restoration projects below
Take a look at three aquatic species habitat restoration projects in more detail below...
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Skookumchuck Early Action Reach
Within the Chehalis Basin, the Skookumchuck River is home to many aquatic species, including culturally-important spring chinook salmon. The Skookumchuck was chosen, along with the Newaukum, Satsop and Wynoochee rivers and Stillman Creek, for early, large-scale restoration. By adding wood, planting native species and removing invasive plants on long stretches of these major rivers, the Chehalis Basin Strategy hopes to make a big improvement quickly for key species like spring chinook.
Large projects like these thrive on collaboration. The state Department of Fish and Wildlife led the project with support from Grays Harbor, Lewis, Mason and Thurston Conservation Districts, Capitol Land Trust, Chehalis Basin Lead Entity, and the private landowners who welcomed the project onto their property.
The Skookumchuck project will be completed in 2021, and the other four projects will be completed in 2022 and 2023.
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Frase Creek Barrier Removal
Frase Creek flows under Pigeon Springs Road north and west of Onalaska in Lewis County. Until November 2019, the culvert through which the creek flowed was three feet above the stream – too steep to let salmon pass. Lewis County replaced the culvert with a large salmon-friendly pipe – opening up more than 2.5 miles for salmon to spawn and grow. This project is one of more than two dozen salmon passage projects funded by the Chehalis Basin Strategy since 2015.
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Oregon Spotted Frog - Salmon Creek
The Oregon spotted frog is a native species of frog considered threatened by the federal government. The amphibians live mostly in open shallow water, like wetlands and slow streams. The frogs and their eggs have been found on the 37-acre parcel identified in the map above. The property will be purchased to ensure the frog’s habitat is not disturbed and can be improved in the future.
All Projects Map
Explore all Chehalis Basin Strategy projects below. Click on the project to discover more information on each project. Filter by "Active," "Completed," "Proposed," and "Canceled" projects
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