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Reservoir Levels and Rainfall – Two Key Factors in Seattle’s Continued Ask to Reduce Water Use  

Seattle’s mountain reservoir levels are significantly below average for this time of year prompting Seattle Public Utilities to continue asking customers to use less water until we get enough rain this fall.

Stories from local media help explain how these aspects impact our region’s water supply 

Understanding Seattle’s regional water supply conditions and why Seattle Public Utilities (SPU) has been asking its 1.5 million customers to use less water for the last several weeks might be puzzling for some. 

Afterall, Seattle is known for its rain, and it’s been raining this fall, right? That’s all true, but unfortunately, it’s not that easy as it involves multiple factors.  

A major factor and perhaps the most important factor in determining the status of the region’s water supply is how much water is currently stored and flowing into our mountain reservoirs. 

This time of year, reservoirs in Seattle’s Cedar River and Tolt River Watersheds are typically at their lowest point due to the summer drawdown as we wait for the fall rains to return in earnest. This year those reservoirs are significantly below average, and weather forecasts are predicting a warmer and drier fall and winter. 

Those two factors have water resource planners at SPU concerned about having sufficient water for people and fish. 

To help better illustrate how reservoir levels and rainfall are affecting water supply conditions, SPU’s Kelly O’Rourke and Alex Chen recently spent time with local media, including reporters from Fox 13 and the Seattle Times, to help tell the story. 

Screenshot of Fox 13 News website form October 11, with headline "Seattle Reservoirs Continue to Drop as Call Continues to Conserve Water."

“I think it is important to provide our customers with an up-close look at our mountain reservoirs, especially since it’s a place that the public cannot access,“ said O’Rourke. “It provides a perspective that I hope better explains our water shortage.”   

Watch the Fox 13 story featuring Kelly O’Rourke and view the mountain reservoir inside the Cedar River Watershed for a closer look at Seattle’s water supply conditions.

Screenshot of Seattle Times website from October 10, 2023 with headline "Recent Rains Not Enough to Fix Water Shortage, Seattle Public Utilities Says."

With our reservoir levels being below average, any rainfall that we get in the mountains is a gift. We’ve received a few inches recently, but as explained in this Seattle Times article, featuring Alex Chen, we need a lot more rain to replenish our water supply.  

Update on Water Usage 

Graph of historical water usage versus current water use, showing use still above the conservation target.

Water consumption for the region continues to slowly go down and we are getting closer to reaching our regional goal of 100 million gallons per day. That‘s good news. As of October 16, our average daily consumption is 109 mgd.

Learn more

We encourage our customers to continue reducing their water usage. There are lots of different ways for all families and businesses to use less water. Go to the Saving Water Partnership or download our water-saving tips flyer in multiple languages

Stay tuned for our next update on the region’s water supply, which will be published on this blog on Monday, October 23.  For more details about the region’s water supply, check SPU’s Water Supply Conditions web page, updated weekly.