For the first time since February 2016, heavy rains and snowmelt in the mountains above Sultan in Snohomish County have caused water levels in Spada Lake Reservoir to reach the Culmback Dam spillway. Much like the extra drain at the top of most bathroom sinks and bathtubs, the spillway allows excess water to safely exit the reservoir long before it can reach the top of the dam.
“Essentially, it means we have more than enough water in the reservoir to run our carbon-free hydropower plant at full capacity,” says Scott Spahr, who oversees Culmback Dam as part of Snohomish County PUD’s Henry M. Jackson Hydroelectric Project. “It’s also a testament to all the safety features built into the dam. The spillway is one of those features, and it’s working exactly as it should.”
Water traveling through the spillway is discharged into the Sultan River, where it flows several miles to join the Skykomish River at Sultan. Areas downstream of Culmback Dam should expect to see some rise in river levels and an increase in river currents.
“We worked in advance to lower the reservoir’s level to make room for much of the rain we expect to get this weekend,” Spahr says. “That has helped to reduce the amount of water traveling through the spillway. Still, we encourage areas downstream to monitor weather and river forecasts, especially with the larger Skykomish River already running high in Sultan. The PUD is monitoring flow rates and river levels, and in contact with local agencies to provide updates as needed.”
Culmback Dam was built in 1965 and enlarged in 1984 to create Spada Lake Reservoir, which provides drinking water to the City of Everett, carbon-free hydropower to more than 53,000 Snohomish County homes and has substantially improved flood control along the Sultan River.
Each year, Culmback Dam is reviewed by the Federal Energy Regulatory Commission (FERC). In its 55 years of existence, the dam has always received FERC’s highest safety rating. The PUD monitors the dam 24 hours a day and conducts regular and extensive on-site safety checks.
To learn more about Culmback Dam, Spada Lake Reservoir and the PUD’s Jackson Hydroelectric Project, click here. For more on Culmback Dam’s safety, click here.