Water Supply

Most of the Watershed lying below an elevation of 1,600 feet consists of a deep porous glacial moraine. A large amount of mountain rainfall flows into 4-mile long Chester Morse Lake, although many streams flowing from the mountains disappear into the ground. Eventually this underground water forms springs in the moraine and is vented back into the river system. The deep moraine provides a natural filtration system, and the Cedar River Watershed is only one of six major drinking-water systems in the country that requires no specially fabricated filtration.

Cedar River water is:

• Screened to remove debris
• Chlorinated to remove microbial contaminants such as giardia
• Fluoridated for cavity control
• PH adjusted for corrosion control

Cedar River water meets or exceeds all federal standards for drinking water, and hundreds of samples are tested for a wide variety of things every day.

Access to the watershed is restricted because people can carry diseases that are most harmful to people, such as cholera and typhoid, which could contaminate the water supply.

The Watershed is a large area of land, bounded by wilderness and the edge of suburban Seattle. Most of the watershed is not fenced except near residential areas and the quality of the water is monitored by a team of seven full-time Watershed inspectors.

From Forest to Faucet

Melting snow and rain are gathered and stored in two reservoirs - Chester Morse Lake and the Masonry Pool created by the Masonry Dam. Built in 1914, the dam releases the water into two large 78 inch penstocks. The penstocks drop water 620 ft. to the hydroelectric powerplant at Cedar Falls. The water is released back into the river and continues to flow for 12 more miles. When it reaches Landsburg, the water is screened and chlorinated before being sent to Lake Youngs. From there, the water is delivered to the taps of nearly 1 million regional residents.

78% of the Cedar River's annual flow continues past Landsburg down the Cedar River into Maple Valley through Lake Washington and out through the Chittenden Locks in Ballard.