Alderwood Water & Wastewater District

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King County's Clean Water Plan - Get Involved!

King County’s Wastewater Treatment Division wants to hear from you about the best ways to make water quality investments for the future. The Online Open House for the King County Clean Water Plan is now open.


When you flush the toilet or take a shower, where does the water going down the drain end up being treated? If you’re an AWWD customer, your wastewater goes to one of three treatment plants: King County’s Brightwater Treatment Plant, AWWD’s Picnic Point Treatment Plant, or the City of Everett’s Treatment Plant.

Here’s a breakdown:

Pie chart of sewer distribution

You may be asking, why does AWWD send so much of the water it collects to King County for treatment? Why doesn’t AWWD treat more water at its own plant?

The answer comes down to one word: gravity. It’s much cheaper to let gravity move water around than to install pumping stations to do the work. Since the 1960s, AWWD has had agreements with King County to treat the majority of the AWWD wastewater flows. AWWD commissioners discovered that it is much cheaper to pay another agency for wastewater treatment service if the water flows by gravity to their treatment plant.

In fact, King County’s Wastewater Treatment Division (WTD) operates three large regional wastewater treatment plants. Together, these three plants treat the majority of King County’s wastewater and are critical assets that protect our region’s water quality.

King County WTD is starting a multi-year planning effort called the Clean Water Plan. It is undertaking this large planning effort because it is facing critical —and expensive— decisions that will affect the region’s water quality. Some questions they are facing include:
• How to make wastewater treatment systems more resilient?
• How to serve a growing population?
• How to further reduce the amount of untreated sewage and polluted stormwater that overflows to local water bodies during storms?
• How to deal with a changing climate?
• How to finance ongoing improvements?

WTD has created an online open house for you to join the conversation. You can also sign up for a mailing list for updates on the plan and invitations to other engagement activities. It’s all on the Clean Water Plan page.

Not sure if your wastewater flows to a King County Treatment Plant? Check this map.