Water Supply Conditions
The current supply conditions for Seattle's regional water system.
June 30, 2025
Last week, the 7-day precipitation total for the period 6/23/2025 through 6/29/2025 was approximately 0.72 inches in the Cedar River watershed and 0.50 inches in the South Fork (S.F.) Tolt River watershed.
Chester Morse Lake at the Overflow Dike was at an elevation of 1557.8 feet, about 1.3 feet lower than last week, and about 2.8 feet lower than its long-term average (based on the years 1990 to 2019). The S.F. Tolt Reservoir at the S.F. Tolt Dam was at an elevation of 1753.8 feet, about 1.7 feet lower than last week, and about 6.7 feet lower than 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 S.F. Tolt Rivers.
Water consumption for the previous seven days averaged approximately 157 million gallons per day (mgd). That is more than the 147 mgd consumed during the same period last year, and more than the 144 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 for this summer. As always, we continue to ask customers to use water wisely. For information about ways to save water, visit www.savingwater.org.
Note:
Regular readers may notice changes to the presentation of the Water Supply Synopsis. These changes bring components of this report into compliance with Web Content Accessibility Guidelines and into line with the City of Seattle style guide. These changes to plot color schemes and to plot layout make it easier for readers with visual impairments to read these charts.
While the presentation looks different, the information in this week’s water supply synopsis and the methods used to calculate these values are exactly the same as they have been in previous weeks.