Key Takeaways
- The Army Corps of Engineers took control of two hydropower dams on the Skagit River to reduce flooding downstream
- The dams, Ross Dam and Upper Baker Dam, were able to hold back 99% of the water flowing into the reservoir, reducing the river’s peak height by 4 to 5 feet
- The operation prevented more severe flooding in the towns of Concrete and Mount Vernon
- The Skagit River’s watershed is mostly wild, with 60% of its flow never passing through a dam
- The Army Corps’ takeover of the dams allowed for strategic water release to mitigate flooding, while also ensuring the dams’ reservoirs had space for the next round of flooding
Introduction to the Skagit River and the Role of Dams
The Skagit River, located in the state of Washington, has recently experienced severe flooding, which was mitigated by the emergency operations of two hydropower dams upstream. The Army Corps of Engineers took control of Ross Dam, a 540-foot tall concrete dam owned by Seattle City Light, and Upper Baker Dam, a 300-foot high concrete dam owned by Puget Sound Energy, to reduce flooding downstream. While big dams have significant downsides, including the impact on salmon populations and the drowning of valleys under reservoirs, they also have major upsides, such as providing climate-friendly electricity and flood control. The operation of these dams highlights the importance of strategic water management in preventing severe flooding and protecting communities.
The Army Corps’ Emergency Operation
As the Skagit River’s flood waters were building, the Army Corps of Engineers took over the two dams to hold back water and reduce flooding downstream. The goal was to prevent the river’s peak height from reaching record levels, which would have resulted in more severe flooding in the towns of Concrete and Mount Vernon. According to Army Corps officials, the dams were able to hold back 99% of the water flowing into the reservoir, with Ross Dam alone holding back a significant amount of water. Although this was not enough to completely prevent downstream flooding, the dam operations were able to shave 4 to 5 feet off the river’s peak height of about 37 feet, according to preliminary estimates. This reduction in peak height made a significant difference in preventing more severe flooding, and the Army Corps’ press release noted that "without this strategic reduction, peak [river] stages in Concrete and Mount Vernon could have been much higher, leading to more severe flooding."
The Skagit River’s Watershed and Hydropower Generation
The Skagit River’s watershed is mostly wild, with 60% of its flow never passing through a dam. The undammed tributaries, including the Cascade, Sauk, Suiattle, and White Chuck rivers, are located high in the North Cascades and contribute to the river’s natural flow. During the Army Corps’ takeover, Ross Dam generated no hydropower, according to Seattle City Light spokesperson Jenn Strang. However, two other City Light dams on the Skagit River continued to produce power, highlighting the importance of hydropower generation in the region. After the flooding risk dropped, engineers started releasing water again to make space in the reservoirs for the next round of flooding, ensuring that the dams’ reservoirs had sufficient capacity to mitigate future flooding events.
The Army Corps’ Ongoing Involvement
The Army Corps of Engineers returned control of Ross Dam to Seattle City Light over the weekend, but took over the dam again as forecasters predicted river flows at the town of Concrete would rise past 90,000 cubic feet per second again. This ongoing involvement highlights the importance of strategic water management and the need for continued monitoring and operation of the dams to prevent severe flooding. The Army Corps’ ability to take control of the dams and release water strategically has made a significant difference in mitigating flooding in the region, and their ongoing involvement will be crucial in ensuring the safety of communities downstream. As the region continues to experience severe weather events, the importance of big dams in providing flood control and climate-friendly electricity will become increasingly apparent, and the Army Corps’ role in managing these dams will be critical in preventing severe flooding and protecting communities.
