Progress across communities, waterways, and projects in 2025

As we look back on a year of progress, the past couple of weeks have been a sharp reminder of why our mission matters. Severe flooding across King County and other parts of the state has pushed rivers over their banks, damaged properties, cut off roads, and disrupted daily life in many communities. As conditions remain challenging, our operators, engineers, and support staff are responding in real time, keeping facilities running and protecting public health and the environment. 

We prepare all year for major storm events, and our work across WTD strengthens our wastewater system now and for the future. This year we have made headway on many fronts, from capital upgrades to partnering on the cleanup of historic pollution, to ensuring we achieve a multitude of benefits from these efforts that reach communities equitably.  

As we navigate the complex clean-water challenges facing our region, here’s a look back at some of the highlights from 2025. 

1. Coal Creek Sewer Upgrade earns Salmon-Safe certification, breaks ground in Bellevue

The Coal Creek Sewer Upgrade Project broke ground this summer to replace nearly two miles of aging pipe so that we can better serve growing populations in Bellevue and Newcastle.

As environmental stewards, we are thrilled to earn the first Salmon-Safe certification for an infrastructure project of this kind in the U.S. This project demonstrates our commitment to protecting a salmon-bearing stream and enhancing the environment by decommissioning old pipes and restoring habitat. The project also builds on improvements the City of Bellevue has made along its Red Cedar Trailhead to make the popular urban hiking trail more accessible. 

2. Contractor networking event builds robust procurement process with qualified local businesses

We hosted King County’s second annual Contractor Outreach and Networking event in the spring and attracted more than 400 people representing local contractors and consultants to King County’s capital projects. With the Wastewater Treatment Division managing the largest capital portfolio within the County, this valuable event supports efforts to create a robust procurement process in an ultra-competitive construction and labor market. It’s also helped ensure economic benefits of projects are felt locally and equitably by businesses of all sizes.

3. West Point Treatment Plant undergoes major upgrades

Construction has kept us busy not just in your neighborhoods but also at our treatment plants, including West Point Treatment Plant in Seattle.  

To modernize our system and equipment, our crews and contractors worked around the clock to relocate equipment, demolish the roof, and reinforce the original concrete pillars as part of the Raw Sewage Pump Replacement Project. Starting next summer, we will replace the first of four 60-year-old biogas-powered pumps and engine with modern electric versions — all while continuing to clean wastewater.

We also replaced two grit classifiers after more than 30 years of operation. Grit classifiers remove sand, gravel, and other fine debris to protect our equipment downstream from additional wear and tear. Low-interest loan funding from the U.S. Environmental Protection Agency’s Water Infrastructure Finance and Innovation Act program and State Revolving Loan Funds help finance these projects so that we can continue cleaning wastewater efficiently and safely and stretch ratepayer dollars. 

Additionally, we installed a passive weir system that safely reroutes excess water out of the plant when flows rise above what the plant can handle. This lowers the plant’s risk of possible flooding, especially during heavy rainstorms.  

Finally, our onsite battery system that provides reliable power to seven critical pumps hit the one-year mark in June. It rode West Point through 78 power disruptions in its first year in operation, including a “bomb cyclone” windstorm in November 2024, with zero wastewater bypasses.  

These projects allow us to operate the plant more efficiently and reliably for decades to come.

4. Second season of construction for the Lower Duwamish Waterway cleanup underway

After wrapping up the first construction season in February, we kicked off the second season of cleanup work in the Lower Duwamish Waterway in October. This season, crews are dredging contaminated sediment and placing clean materials near the South Park Bridge, Duwamish Waterway Park, and Duwamish River People’s Park.  

In partnership with the City of Seattle and Boeing, we are currently removing contaminated sediment from the uppermost segment of the five-mile stretch designated as a U.S. EPA Superfund site to enhance the health of the river for people and fish.  

We’ll wrap up this season’s work in February 2026, and then later in the fall move into the third and final season of upper reach section of the cleanup. In-water construction activities are restricted to these months to protect certain fish species. 

5. Major sewer pipe rehabilitation in Auburn to extend service life

In September, we began work on one of our largest sewer rehabilitation efforts: the M Street Trunk Rehabilitation Project in Auburn.  

Using advanced trenchless technologies, such as cured-in-place pipe and spiral-wound lining, we are repairing the pipes from the inside and minimizing disruptions in this densely populated area.  

The project will repair corroded sewer pipes, extending their service life for decades to come. The project will also restore 45 maintenance holes and 100-plus side sewer connections that link homes and businesses to the trunk.  

We completed 0.6 miles of pipe this year, with the remaining 2 miles scheduled for next summer. 

Heading into 2026, work continues with a clear focus on reliability, resilience, and service to our communities. We’ll keep building on what’s in motion, responding to challenges as they come, and doing the steady work that protects public health and the environment every day.