Ask the Engineer: Where Does Our Water Come From?

You turn on the faucet and water comes out but where does it come from? We here in the Pacific Northwest have it good, nature does most of the work for us. Throughout the fall and winter when water use is down, precipitation falls in the mountains and turns into snowpack. When it starts to warm up in the spring, all that snow melts and sends us a steady flow of clear, clean water.

photo 1 (1)
Spada Lake is about 25 miles east of Everett

The water that comes out of your faucet has its beginnings in the Cascade Mountains. More specifically the Sultan Basin Watershed, considered one of the nation’s purest and most abundant water sources. A watershed is simply the area of land where all of the water that is under it or drains off of it goes into the same place. That place is Spada Lake or the Spada Reservoir.
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The Spada Reservoir was created in 1964 by the City of Everett in partnership with Snohomish County PUD. A dam was constructed on the Sultan River to hold back water, 50 billion gallons of water. Rain and snow melt from the surrounding Cascade Mountains flows into Spada Reservoir. The Sultan Basin Watershed covers an area of about 84 square miles (about 10 times the City of Lynnwood) and the average annual rainfall is about 165 inches, or 5 times our local rainfall.

Water transmission line near Highway 2
Water transmission line near Highway 2

From Spada Reservoir, the water travels 8 miles through a pipeline to a hydroelectric powerhouse and then to the City of Everett Treatment facility at the Chaplain Reservoir. Here the water (about 50-million gallons a day) is filtered and disinfected and then travels in four 4-foot pipes towards Everett. Three of these pipes can be seen from the trestle on Highway 2 east of Everett. Two of these transmission lines carry treated drinking water, a third carried untreated water for industrial use at Kimberly-Clark paper mill up until the plant closed in 2012. A fourth line takes a southern route and can be seen from Homeacres Road west of Snohomish.

At this point much of the water goes to serve the City of Everett but a large portion is sold off to serve the majority of the remainder of Snohomish County. Over 50 water systems obtain their water from the City of Everett to serve over half a million residents.

The Alderwood Water District obtains water from the City of Everett and provides water to the City of Lynnwood*.

The City of Lynnwood has over 169 miles of distribution water mains, a three million gallon reservoir and a 2.77 million gallon reservoir, and one pumping station which all work together to bring clean water right to your faucet.

*Some parts of Lynnwood are served by the Alderwood Water District directly, not the City’s water system.

Dustin DeKoekkoek, P.E. is a civil engineer with RH2 and designs public infrastructure projects all over the Pacific Northwest. Have a question about the topic covered here or for a future “Ask the Engineer” column? Email Dustin at or leave a comment below.  You can also connect with Dustin on LinkedIn here.
  1. Mr. DeKoekkoek,
    This is Bernard Spada Jr. Can you tell me how Spada Lake got it’s name? Just curious as my name is Spada. I know where those Spada’s came from. (Italy)
    Thank you

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