A More Secure Future for Flood Control
Dike in Mount Vernon. Photo from Skagit River History
The bulk of Skagit’s agricultural fields sit in floodplains with world-class soils and a vulnerability to flooding. The extensive dike and levee system makes farming in this lowland possible. But those levees only protect against 25-year floods, so it is important to reduce risks in all possible ways.
“The thing that saves our bacon is the drawdown behind the hydroelectric dams,” explained Will Honea, the Skagit County Prosecuting Attorney, Senior Deputy for Natural Resources.
Ross Dam
The drawdown Honea referred to is negotiated into the license that governs how Seattle City Light (SCL) operates its dams on the Skagit River, Ross Dam being the most significant. The licenses for SCL’s Skagit River Hydroelectric Project do not get renewed often — every 30 to 50 years. When a project’s license is up for renewal, like it is now, stakeholders seize the opportunity to negotiate and improve operations.
The current license guiding Seattle City Light expires in 2025. Since 2020, the public utility has been negotiating with many local partners over a range of issues ahead of its application for a new license to be issued by the Federal Energy Regulatory Commission. One of those issues is flood control, including the drawdown, which in this case is primarily the release of water behind Ross Dam.
Ross Dam Construction 1947. Photo from Seattle City Light
When the dam was first constructed in the 1940s, the Army Corps of Engineers recommended a storage capacity of 200,000 acre feet, but instead, the current license sets flood storage at Ross Dam at 120,000 acre feet to be available by December 1. That is, the reservoir behind the dam has the capacity to store 120,000 acre feet by the first of December.
That storage helps protect against storms and extreme rain events, like atmospheric rivers, that dump large amounts of rain and threaten downstream communities and farmland, which occurred in the November 2021 flood.
That flood had been fresh on the minds of the Skagit team focused on renegotiating the flood control elements of the license, among other key concerns such as fisheries management and recreation.
Representatives from Skagit County government, the Skagit Dike District Partnership, and the Skagit Drainage and Irrigation Districts Consortium collaborated on an integrated plan. For more than a year they worked closely with city governments, state and federal resource agencies, and local tribes, especially the Upper Skagit.
“Working together in good faith, tribes and districts, the county, tribal, and local government of the Skagit can solve these complex natural resources problems,” Honea said.
Reducing the risk of flooding presents a significant challenge. Raising the levees is thought to be prohibitively expensive, with costs possibly running into the billions. One way to pay for that would be through development, but Skagit County and a majority of its citizens are committed to preserving this area as farmland. A 2024 survey by the Skagit County Planning Commission found that the community’s number one priority for the next 20 years was the preservation of agricultural land.
Some constituencies wondered that if the negotiations produced stronger flood control measures, would that allow for fewer restrictions and more development in the floodplain. That is not the case.
“This is about protecting existing infrastructure. This is not about promoting new growth on the floodplain,” said Honea. “Quite to the contrary. We have pledged not to do so as a condition of this flood protection.”
The drawdown behind Ross Dam, said Honea, is “the single most important and single most cost-effective flood risk mitigation measure.”
The stakes for getting this right are high.
2021 Skagit Flood by Megan Farmer
The November 2021 flood is instructive in multiple ways. First is its November date. Second is its size. Roughly 170,000 acre feet were stored in Ross Lake at the time of the flood — significantly more than the license demands. Had the levels been at the license’s minimum, the flood might have been eight feet higher and flowing through downtown Mount Vernon.
The local team developed an integrated plan that included several components. For the critical flood control part, the negotiating group sought two changes.
One was to increase flood control capacity.
The local team asked for the 200,000 acre feet the Corps originally recommended, something local communities also supported.
The second change requested was when the drawdown occurred — that is, when the flood storage capacity behind the dam reaches the target. The current license sets that deadline as December 1, which history indicates is not early enough in the year. Major floods in the last three decades have happened almost entirely before December 1. Climate change scenarios predict earlier floods will continue. As a result, the County, Consortium, and Partnership asked for the drawdown to occur a month earlier, by November 1. Moving the drawdown date back a month reduces flooding risks and better aligns with seasonal realities.
The local team managed to agree to new terms with SCL following negotiation, marking a significant change. The new flood storage figure has been increased to 140,000 acre feet with an additional operational buffer set at 165,000 acre feet.
Even more important is the change of the drawdown date to November 1 for those 140,000 acre feet. Under the current license, on November 1 only 43,000 acre feet need to be available. The new date is a notable, helpful change that will reduce flood risks.
“What that means for the people of Skagit County,” said Jenna Friebel, the executive director of the Skagit Drainage and Irrigation Districts Consortium, “is that we have almost another entire Baker Lake plus some in early season flood storage which is going to give us a lot more flexibility to reduce flood risk down in our community.”
Friebel was pleased with the outcome. “We have a great deal on flood control,” she said.
Obtaining these changes has been a long time coming.
“This is the first time in the history of these dams that the Skagit Valley is obtaining adequate, safe flood storage,” said Honea.
Story by Adam Sowards