Water Supply Conditions

Masonry Pool Reservoir
Chester Morse Lake Reservoir - This photo was taken on August 9, 2020 by Kevin Johnson.

Below are current supply conditions for Seattle's regional water system. 

August 11, 2020 

Last week, 0.23 inches and 0.81 inches of precipitation were recorded in our Cedar River and South Fork Tolt River watersheds, respectively.

Chester Morse Lake at the Overflow Dike was at elevation 1556.2 feet, about 1.2 feet lower than last week, and about 1.9 feet above its long-term average (based on the years 1990 to 2019). Masonry Pool Reservoir at Masonry Dam was at elevation 1556.1 feet, about 1.3 feet lower than last week, and about 5.9 feet above its long-term average. The South Fork Tolt Reservoir at the South Fork Tolt Dam was at elevation 1756.2 feet, about 2.0 feet lower than last week, and about 5.0 feet above its long-term average. Water releases from reservoir storage are actively being managed for water supply, fish habitat and flood management objectives for both the Cedar and South Fork Tolt Rivers.

Water consumption for the previous seven days averaged approximately 161 million gallons per day (mgd). That is lower than the 166 mgd consumed during the same period last year, and less than the average of 174 mgd used during the same period over the years 2010-2019. 

Based on current conditions and forecasts, Seattle anticipates the regional water system will have sufficient water supply for people and fish this summer.

As always, we continue to ask customers to use water wisely. For information about ways to save water, visit www.savingwater.org.


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