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Wastewater programs

Learn about our programs to improve water quality, plan and prepare our wastewater system for regional growth, and protect public health and the environment.

Accessibility standards

Learn about the Wastewater Treatment Division Americans with Disabilities Act (ADA) Accessibility Program and accessibility standards implemented by the division.

Conveyance System Improvement

The Conveyance System Improvement Program looks at ways to improve the King County wastewater conveyance system and address public health concerns, while ensuring that the system has sufficient capacity to respond to regional growth.

Duwamish Waterway programs

The Wastewater Treatment Division and its predecessor, Metro, have worked for more than 40 years to restore the Lower Duwamish Waterway.

Duwamish River Valley Groundwater Study

Learn about the Duwamish River Valley Groundwater Study that will help King County understand how groundwater in this coastal area is impacted by climate change, flooding, and tidal changes.

Infiltration and Inflow Control Program

The Infiltration and Inflow Program collaborates with local sewer agencies to reduce stormwater (infiltration) and groundwater (inflow) from entering the sanitary sewer system, maintaining pipe capacity for sewage and reducing the need to add sewer system capacity. 

Mouth of Duwamish Wet Weather Facilities

Find information and facts about planned wet weather facilities in and around SODO, including current and future projects, background on combined sewer overflows, environmental benefits, and public engagement.

Protecting Our Waters (controlling combined sewer overflows)

Protecting our Waters is King County’s program to prevent pollution caused by excess stormwater in the sewer system on rainy days.

Be RainWise

The RainWise program provides rebates to private property owners in eligible areas to install rain gardens and cisterns to help manage the rain that falls on their roofs. 

Regulatory compliance and land acquisition services

The Regulatory Compliance and Land Acquisition Services unit handles the real property and permitting needs for all Wastewater Treatment Division projects.

Sediment Management Program

The Sediment Management Program is responsible for implementing the King County Sediment Management Plan, which addresses historical sediment contamination near County combined sewer overflow outfalls.

Treatment Planning Program

Our Treatment Planning program carefully evaluates current and forecasted capacity needs and regulatory requirements, helping King County make the right decisions and investments, at the right time, for the most effective treatment of the region’s wastewater.