The Washington Department of Ecology and the U.S. Environmental Protection Agency (EPA) have issued fines to the City of Seattle and King County for violations of federal and state regulations governing combined sewer overflows (CSOs). The penalties stem from multiple discharges of untreated or partially treated sewage that occurred throughout 2023.
Seattle faces a total penalty of $71,000, while King County has been fined $46,000. Both penalties are tied to violations of the federal consent decrees and state water quality permits that require the city and county to reduce combined sewer overflows into local waterways.
Seattle Discharges
The City of Seattle was penalized $50,000 for 20 sanitary sewer overflow (SSO) events. Unlike CSOs, which can occur during extreme weather, SSOs are prohibited under Seattle’s discharge permit regardless of weather conditions. Several overflows resulted in untreated sewage reaching Puget Sound, Lake Washington, Lake Union, the Ship Canal, and the Duwamish River, while others caused sewage backups into homes and buildings.
Additionally, the city was fined $21,000 for seven wet weather overflows. These incidents, though weather-related, were attributed to failures in operating or maintaining sewer systems.
King County Discharges
King County’s penalties include $40,000 for water quality violations at its Elliott West, Carkeek, and Alki CSO treatment facilities. At various times, discharges from these facilities failed to meet requirements for disinfection and standards for pH levels, fecal coliform bacteria, residual chlorine, and solids that can pollute waterways.
The county was also fined $6,000 for two wet weather-related sewer overflows caused by maintenance or operational issues. These violations do not involve King County’s primary wastewater treatment plants — Brightwater, South Plant, and West Point — which are outside the scope of the consent decree.
Consent Decrees and Long-term Plans
The penalties are required under federal consent decrees negotiated between the City of Seattle, King County, the EPA, and the Department of Ecology in 2013. These agreements were established to settle past violations and reinforce compliance with state regulations for combined sewer systems.
Combined sewer systems, which carry both stormwater and sewage, were originally designed to release excess flows through overflow points, or outfalls, during heavy storms. However, under state and federal law, such releases must now be minimized to protect waterways like Puget Sound, lakes, and rivers.
Recently, the EPA and Ecology agreed to modify the consent decrees to give Seattle and King County more time to address larger infrastructure projects resilient to climate change. The timeline for controlling all CSO outfalls has been extended from 2030 to 2037. These modifications prioritize projects in the Lower Duwamish Waterway area and allow flexibility for both jurisdictions to adapt plans as new opportunities and information emerge.
The U.S. Department of Justice lodged the modified agreements in federal district court on Nov. 15, 2024. Public comments on the modifications are being accepted through Dec. 23, 2024.
Impact of Combined Sewer Overflows
Untreated or inadequately treated sewage discharges carry bacteria and pollutants that can pose risks to humans, animals, and the environment. Contamination from sewage can make rivers, lakes, and Puget Sound unsafe for recreation, fishing, and wildlife habitat.
Seattle and King County are continuing efforts to reduce combined sewer overflows through significant infrastructure investments and ongoing maintenance improvements.
Under the terms of the penalties, Ecology and the EPA will split the payments evenly. The portion collected by Ecology will be placed into the Coastal Protection Fund, which provides grants to public agencies and Tribes for water quality restoration projects across the state.
Both Seattle and King County have committed to controlling combined sewer overflows under state regulations by 2037. While both have completed multiple projects to reduce CSO discharges in recent years, further investments and improvements remain necessary to meet long-term water quality goals.