Seattle Public Utilities - Seattle's Water Supply

Seattle's Water Supply

SPU owns two water collection facilities: one in the Cedar River watershed, which supplies 70 percent of the drinking water used by 1.3 million people in Seattle and surrounding suburbs (primarily the city south of the Lake Washington Ship Canal) and the other in the Tolt River watershed which supplies the other 30 percent (primarily the city north of the canal).

From the city's founding through the 1880s, Seattle's water was provided by several private companies. In a July 8, 1889 election, barely a month after the Great Seattle Fire (June 6, 1889) gave a dramatic illustration of the limitations of the city's water supply, Seattle's citizens voted 1,875 to 51 to acquire and operate their own water system. In accordance with this vote, the city Water Department acquired the Lake Union and Spring Hill plants for $400,000.

This was understood from the first to be only a temporary expedient, inadequate to the expected growth of the city. Attention soon focused on the Cedar River, an idea first proposed in the 1870s; the question was how to bring that water to the city. From 1892, the responsibility for doing so fell to newly hired City Engineer Reginald H. Thomson and his assistant George F. Cotterill. Besides the technical challenges, they and a series of Seattle mayors had to keep the citizenry on board to move forward with this expensive project through the Panic of 1893.

The Klondike Gold Rush put Seattle on a sound economic footing. The 1901 completion of Cedar River Supply System No. 1 (active from February 21, 1901) gave the city a steady supply of clean water with an intake 28 miles from the city itself; this was supplemented by Cedar River Supply System No. 2 in 1909. Together, these systems gave the city a supply of more than 60,000,000 US gallons (227,125 kl) of water a day.

The original Cedar River pipeline was made of reinforced wooden pipe "big enough so a small boy could stand upright in it" and carried 22,500,000 US gallons (85,172 kl) of water a day. By 1950, three big mains carried up to 162,000,000 US gallons (613,237 kl) of water a day.

To guard against contamination at the source, the city purchased or otherwise gained control of 142 square miles (370 km2) of land and placed it under the jurisdiction of the Department of Health and Sanitation. The city also established an extensive system of reservoirs within city limits. By 1919, six reservoirs had a combined capacity of 270,000,000 US gallons (1,022,061 kl). In 1950, the city owned "about two-thirds" of the watershed, the federal government "about one-fourth"; the remainder, "around eleven square miles," was owned by private lumber companies.

Seattle has at times contracted to provide water for entities out outside of city limits.

In recent decades, the Seattle Regional Water System has significantly improved conservation. Current usage is roughly equal to usage in 1960, despite roughly a 35% increase in population over that period.