By Steven Schauer, Deputy Executive Director
The King County Flood Control District (KCFCD), in partnership with King County as a service provider, recently completed a critical assessment of levee systems along the Raging River. This project aimed to evaluate potential weaknesses in the existing levee system, understand the consequences of a levee breach, and determine next steps to enhance public safety and flood resilience.
Why Study Levees?
Most levees in King County were built in the 1960s or earlier, with limited records on their construction. While some levees have undergone repairs, many do not meet modern design standards. A levee breach can lead to unexpected and severe flooding, threatening homes, businesses, transportation infrastructure, and public health and safety.
“This study is a critical step in ensuring the safety and resilience of our communities,” said Michelle Clark, Executive Director of the King County Flood Control District. “By understanding the risks and taking proactive measures, we can better protect homes, businesses, and infrastructure from future flood events. The Flood Control District remains committed to building a future to withstand flood risks where thriving King County communities and healthy ecosystems coexist in harmony with area rivers.”
What is a Levee Breach?
Levees are designed to contain floodwaters and protect nearby communities. However, they can fail if flood levels exceed their capacity or if structural weaknesses develop. Though rare, levee breaches can have devastating consequences. Past levee breaches on the Tolt River (2009) and the Cedar River (2020) highlighted the need for proactive assessment and risk management. Identifying and mitigating these risks is essential to safeguarding residents and infrastructure.
Research and Key Findings
King County, as service provider to the KCFCD, conducted a comprehensive risk assessment, analyzing:
- Possible levee failure scenarios
- Breach risks at various flood levels
- Climate change impacts on flooding frequency and severity
- Economic and community vulnerabilities, particularly for low-income populations
The assessment focused on the lower 1.5 miles of the Raging River, extending to its confluence with the Snoqualmie River near Fall City. The study found that the likelihood of a levee breach in this area is very low, thanks to the levees’ strong construction and stable foundations. However, some risks remain:
- Floodwaters can overtop levees when both the Raging and Snoqualmie rivers experience high flows.
- Climate change is expected to increase the frequency of extreme floods, raising future levee breach risks.
- Earthquakes could heighten the risk of levee failure.
Next Steps for Public Safety
To maintain and improve flood safety along the Raging River, the KCFCD and King County will:
- Collaborate with public safety agencies to enhance emergency preparedness.
- Educate residents about best practices for living near levees.
- Continue regular levee inspections and maintenance to ensure structural integrity.
- Explore re-enrolling the levee system in the U.S. Army Corps of Engineers maintenance program to access additional resources.
- Incorporate findings into planning future flood resilience projects for the Fall City area.
How You Can Help
Residents living near levees play a crucial role in maintaining flood protection systems. You can help by:
- Avoiding planting, cutting, or removing vegetation on levees.
- Keeping levees free of structures, fences, and debris.
- Reporting any maintenance concerns to King County staff.
- Allowing County personnel access to levees for inspections and repairs.
Looking Ahead
The Raging River levee assessment is part of a broader effort to ensure that King County’s flood protection infrastructure remains strong and effective. By combining scientific research, proactive maintenance, and community collaboration, the King County Flood Control District and King County are working to reduce flood risks and protect local communities for years to come.