Seattle Public Utilities Mami Hara, General Manager/CEO

Watershed Protection

  • SPU water supply and distribution system.

The production of high-quality water starts at the source—the Cedar River Watershed.

The watershed encompasses 90,500 acres of forest land. Below an elevation of 1,600 feet, most of the watershed consists of a deep porous glacial moraine, which is the rock, gravel, sand and clay left by glaciers. The deep moraine provides a natural filtration system. The Cedar River Watershed is one of only six major drinking-water systems in the country that do not require a filtration treatment system.

Access to Lake Youngs is restricted because people can carry diseases that could contaminate the water supply. A team of full-time watershed inspectors monitor the quality of the water. Cedar River water meets or surpasses all federal standards for drinking water, and hundreds of samples are tested for a wide variety of substances every day.