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What we do

WTD is an innovative clean-water enterprise that protects public health and water quality by providing wholesale wastewater treatment services to 17 cities, 17 local sewer districts and more than 1.6 million residents across a 420-square-mile area in King, Snohomish and Pierce counties.

More than 650 WTD employees manage the regional system of treatment plants, pipelines and pump stations that operate around the clock. They also plan and design new facilities, regulate the disposal of industrial waste, educate the public and businesses on pollution prevention, and pursue innovation by recycling resources to support sustainable communities.

2016 accomplishments

Plant operation

West Point Treatment Plant celebrated 50 years of service. Regional wastewater treatment has cut pollution to the Duwamish River, and transformed Lake Washington to one of the world’s cleanest urban lakes.

All five treatment plants attained 100 percent compliance in meeting state and federal effluent limits. Vashon Treatment Plant earned a platinum level award for compliance with all permit conditions over a period of five consecutive years.

Brightwater Treatment Plant earned the Department of Ecology’s “Outstanding Wastewater Treatment Plant” award, which is only given to facilities achieving perfect performance in a reclaimed water process that depends on compliance from operations to its customers.

Resource recovery and recycling

Between West Point and South treatment plants, WTD produced 33,600 megawatt hours of electricity, enough to power nearly 4,000 homes.

In addition, WTD cut electricity usage by 800,000 kilowatt hours by installing programmable thermostats in six pump station HVAC systems. Once all pump stations are equipped, the division expects to reduce offsite electricity by 10 percent.

One-hundred percent of the division’s Loop® biosolids were recycled for use in forestry, agriculture and commercial composting applications.

Education, outreach, and community services

WTD continues to promote education about clean water systems and careers in diverse communities. The division hired 10 high school students for an internship learning about water systems, equity and social justice, and careers in wastewater.

WTD’s project team working on the Georgetown Wet Weather Treatment Facility completed a design advisory group effort.

This year marked the five-year anniversary of WTD’s partnership with IslandWood that has reached almost 60,000 people through clean-water education programs.

Pollution control and cleanup

In July, King County approved 11 WaterWorks Grant Program awards to address water quality issues. The City of Kent’s Leber Homestead Arsenic Remediation Project led to completion of off-channel salmon habitat and floodwater storage.

In the fall, King County participated in the “Make a Difference Day” planting event at the Georgetown Green Wall, a community driven air quality project funded by WTD’s Green Grants Program.

WTD’s Murray Wet Weather Storage Facility began operations in November. This facility protects Puget Sound by reducing untreated discharges of stormwater and wastewater off Lowman Beach Park in West Seattle during heavy rainstorms.

WTD led the design and contracting for exploring cleanup technology for the Lower Duwamish Waterway Group, including testing activated carbon for sequestering pollutants.

Finance and administration

Excellent credit ratings and continued favorable financial market conditions combined  to benefit ratepayers served by WTD. King County sold $500 million of sewer revenue bonds in September, essentially re-financing its debt to save $104 million over the next 33 years.

WTD maintained a strong sewer revenue bond rating with sound management practices and consistent financial performance.

WTD received recognition by the “Utility of the Future-Today Joint Recognition Program,” which is supported by the U.S. Environmental Protection Agency. WTD was one of 61 recipients recognized nationally for optimizing operations, meeting or exceeding regulatory requirements, and engaging employees and communities.

Capital projects

The division invested about $207 million in capital improvement projects to add system capacity, replace or rehabilitate aging facilities, and enable efficient operations.

The Fremont Siphon Replacement Project was completed and includes two new pipelines tunneled under the Lake Washington Ship Canal to replace World War I-era pipes.

The RainWise partnership between King County and the City of Seattle marked the 1,000th installation of green stormwater features on private property that will reduce annual stormwater runoff by up to 16 million gallons.


The division will maintain its commitment to service excellence by increasing efficiency through Lean and continuous improvement; meeting or surpassing permit requirements; exploring new technologies and markets for its recycled products; restoring the West Point Treatment Plant; and investing in its asset management and capital improvement programs.

2016 annual report coverEnvironmental Stewardship in King County, 2016

"Environmental Stewardship in King County," the 2016 annual report for King County Department of Natural Resources and Parks, describes the department, what it was tasked to do, and what it accomplished in 2016.

Celebrating 50 years of work to keep our waters cleanWTD celebrated the men and women who have dedicated their careers to clean water service.

1610_utility-of-futureActing Director Gunars Sreibers and Assistant Director Sandy Kilroy celebrate the people and energy that earned WTD’s recognition. 

crane-rosette-with-CTC-sampling-bottles_600The County’s marine water quality monitoring program collects and analyzes water quality samples at 12 offshore sites and 20 beach locations.