Green Stormwater Infrastructure in the Duwamish Valley

By Yordanos Tesfazion

The Community Voices blog documents stories of our parks and public spaces and the people behind them. At Seattle Parks Foundation, we collaborate with hundreds of partners, volunteers, organizations, and city agencies who are working towards building a region that can withstand our current climate emergency. This piece is the fifth in our Partner Powered Futures series, dedicated to highlighting how they utilize parks and public spaces to foster inclusive communities and grow urban resilience.

The beauty of the Puget Sound region draws millions of tourists from around the world. According to Visit Seattle, 39.7 million people visited Seattle and King County in 2025. King County is also the 13th most populous county in the nation, and while recent numbers indicate a slight decrease in population growth, there’s still a healthy flow of migration in and out of the region.

What makes the area a hot spot for local and tourist activity—why do people visit, move, and live here? This corner of the country offers what few places in the world can: mountains, waters, acres of forests, city views, and four seasons (most years). These perks, however, aren’t without regional challenges.

King County experiences annual cycles of flooding that impact the South End and South King County the hardest. Several communities across King County sit along major river systems that mostly flow through the Cascades, making them hazardous during flood season. The combination of heavy precipitation like rain and snow and other weather patterns put some King County residents at increased risk of experiencing severe flooding on a near-annual basis.

“Flooding remains the most common natural hazard in King County, and it can happen at any time during the year. The threat of flooding and any potential impacts and risks can never be fully eliminated, but it can be reduced by being proactive."

Steven Schauer, King County Flood Control

GSI Partnerships in the Duwamish Valley

In the South End of Seattle, major flooding events over the past several years in Duwamish River communities have devastated neighborhoods like South Park, serving as a warning for its neighbor, Georgetown, another low-lying community that sits on the Duwamish River Delta. The area’s struggles with chronic flooding are linked to its lengthy history of environmental injustices and outdated infrastructure, ranging from heavy pollution to inadequate drainage systems. Not to mention its proximity to the contaminated Lower Duwamish Waterway, federally recognized as a Superfund Site. These neighborhoods, home to Seattle’s most diverse communities, also have a large population of lower income individuals and families, many who belong to underrepresented groups with limited access to resources and decision-making powers.

Today, it’s clearer than ever that our current infrastructures can’t withstand the effects of global warming. Millions of dollars have been invested into the South End to protect Duwamish River communities and rectify the impact of repeated systemic shortcomings. In the last two decades, the City of Seattle and the King County Flood Control District (unaffiliated with King County) have had a strong presence in the area, partnering with neighborhood groups and community organizations like our strategic partner Duwamish River Community Coalition (DRCC) to combat flooding and mitigate future flood risk. Projects they’ve collaborated on include the $25 million South Park Drainage and Roadway Partnership funded by a 2015 transportation levy and $33 million South Park Pump Station.

These initiatives are examples of long overdue yet collaborative Green Stormwater Infrastructure (GSI) projects implemented in the Duwamish Valley by municipal agencies to support climate resilience. Flooding isn’t uncommon in Duwamish River communities but devastating flooding in December 2022 displaced dozens of South Park residents from 25 homes and damaged numerous local businesses, bringing attention to major gaps in infrastructure and preparedness while also demonstrating the value of GSI. The South Park Drainage and Roadway Partnership and South Park Pump Station projects address notorious sewer and drainage concerns the South End has dealt with for decades. Both projects were completed by 2023, with multiple street upgrades designed to reduce flooding in South Park. The addition of pumps helping to push excess and polluted stormwater runoff to the Duwamish Waterway during high tide events also reduces flooding on the roads.

Building Long-Term Climate Resilience Through Education, Training, and Advocacy

According to American Rivers, GSI is an approach to water management that mimics the natural water cycles through actions like tree planting and wetland restoration, incorporating natural environment and engineered systems to clean water and conserve ecosystems. In addition to its restorative and protective qualities, GSI is also effective, economical, and improves community safety and quality of life.

Experts warn that global warming will cause sea levels to rise by around three feet over the next century. With increased climate threats on the horizon, the City of Seattle and King County Flood Control District have funded several neighborhood groups in the South End such as our community partners Dirt Corps, Duwamish Valley Sustainability Association (DVSA), and Georgetown Open Space & Youth Council. These groups have been building climate resilience in their communities to equip neighbors with the tools, skills and knowledge through outreach, education, job training, and mentorship surrounding GSI and advocacy.

Through their projects, our community partners are proactively shaping the Duwamish Valley’s future and ability to respond to climate-induced threats and emergencies with their GSI work, making their neighborhoods more self-reliant and safe. This work isn’t carried out alone. Partnerships are powerful, and in addition to our fiscal sponsorship program, our community partners receive additional support from other organizations, municipal agencies, volunteers, and grants.

Among many other projects throughout the years, Dirt Corps has recently planted trees and shrubs and cobbled the inlet and outlet on 4th Avenue. Heavy rain in late spring led them to adapt improvements with additional erosion control features, making full infiltration possible in just a few hours. Swales on Homer Street and Findlay and 7th Avenue were transformed with replacement soil and erratic rock placement. They also placed 10 Grattix boxes that act as rain gardens, dividing heavy flow from large roof areas to the Grattix box and overflow to the side sewer to prevent overwhelming flooding during heavy rainfall. Dirt Corps is a key supporter of GSI efforts in the Seattle area, with the City providing them $342,000 in funding since 2022.

DVSA and Vila Comunitaria, with the support of Architect Meredith Hall, presented green infrastructure designs for the South Park Neighborhood Center, a designated historical Seattle landmark. They shared the designs with the building’s tenant group and the City of Seattle’s Finance and Administrative Services facilities team prior to starting their permitting process. The project team also established a partnership with Dirt Corps, who will not only lead the construction phase of improvements, but also donate two Grattix boxes to be installed at the South Park Neighborhood Center. In August, DVSA put together an open-house style community event to introduce the project to the neighborhood and encourage participation and feedback.

Georgetown Open Space & Youth Council participated in restoration efforts at Gateway Park North and letter-writing campaigns. During the cooler months, they took their work indoors and continued their advocacy and organization, while also learning about GSI like green wall design and planning. Another collaborator of Dirt Corps, they also recently worked together to build the Glass Eye Studio green wall in South Park, wrapping the entire building.

It Takes a Village to Preserve a Village

Displacement by climate change is a growing concern for South Park and Georgetown communities. The implementation of GSI throughout Seattle’s South End and beyond serves the purpose of preserving the natural land, resources, and lives of residents and wildlife who reside in the region. From the construction of green projects to offering hands-on training and education to those living in the area, our partners are addressing pressing concerns currently impacting their neighbors while simultaneously promoting climate resilience by providing affected populations with the confidence and experience to protect their communities.

Better yet, because this work is community-led, our partners foster a type of community camaraderie that can fundamentally shape how future generations approach similar efforts. In coming together to protect the places they call home, they’re increasing the chances of those places existing for years and years. Without the partnerships that’ve been formed in the Duwamish Valley over the last several decades, what would the region look like today?