Seattle Public Utilities

Current Water Supply Conditions

  • Masonry Pool ReservoirChester Morse Lake Reservoir – This photo was taken on May 20, 2018 by Lilliana Pando.

May 21, 2018

Last week, 0.69 inches and 0.58 inches of precipitation were recorded in our Cedar River and South Fork Tolt River watersheds, respectively.  Spring season snowmelt from the upper mountain basins above our water supply reservoirs is occurring and snowpack levels are close to the long-term median for this time of the year.

Spring reservoir refill operational targets are being met.  At the beginning of this week Chester Morse Lake at the Overflow Dike was at elevation 1563.8 feet, about 2.4 feet higher than last week, and about 4.0 feet above its long-term average (based on the years 1985 to 2014).  Masonry Pool Reservoir at Masonry Dam was at elevation 1563.7 feet, about 2.4 feet higher than last week, and about 4.1 feet above its long-term average.  The South Fork Tolt Reservoir at the South Fork Tolt Dam was at elevation 1764.1 feet, about 0.4 feet higher than last week, and about 1.9 feet above its long-term average.  Water releases from reservoir storage are actively being managed for water supply, hydropower, fish habitat and flood management objectives for both the Cedar and South Fork Tolt Rivers.

Water consumption for the previous seven days averaged approximately 134 million gallons per day (mgd).  That is higher than the 106 mgd consumed during the same period last year, and more than the average of 128 mgd used during the same period over the years 1999-2014. 

Related Links

Current water supply graphs (pdf)
Landsburg Mitigation
Water Sources and Treatment