SEATTLE -- In response to the region’s ongoing drought, Seattle City Light and the Skagit Flow Coordinating Committee have decided to reduce flows from Ross Lake through City Light’s dams on the Upper Skagit River.
The new flow plan is designed to avert a potential disaster for Skagit River fish, should the current drought continue into the next water year.
“If the drought lasts longer than just this year, then the worst thing for fish would be to head into another water year without a full reservoir,” said City Light Superintendent Gary Zarker. “We can reduce flows now without significant harm to fish, and that gives us a tool to protect fish if our drought continues.”
The lower flows are scheduled to begin April 1. The plan is expected to have no impact at all on Chinook salmon nests in the Upper Skagit. It potentially could affect 1 percent or less of chum salmon nests between Newhalem and Rockport. The impact on steelhead nests created this spring is also expected to be minimal.
“There is a reasonable chance that we can protect 100 percent of all three species’ nests, if nature cooperates with timely rain this spring,” said City Light fisheries biologist Dave Pflug.
The threats to fish will be much greater this summer through next fall and winter if the drought continues and Ross Lake levels are allowed to drop, Pflug said.
City Light, Seattle’s municipal electric utility, owns and operates three dams on the Skagit River. The utility manages flows on the river between Newhalem and Marblemount in partnership with other members of the Skagit Flow Coordinating Committee. Those members include the U.S. Fish and Wildlife Service, the National Park Service, the U.S. Forest Service, the National Marine Fisheries Service, the Washington Department of Fish and Wildlife and the Skagit System Cooperative, a consortium of Native American tribes.
The region’s drought has drastically reduced natural flows into Ross Lake. Since November, City Light has been carefully limiting the amount of water released from the reservoir into the Upper Skagit.
“We’ve been letting enough water out to protect 100 percent of the salmon redds in the Upper Skagit, but not enough to deplete Ross Lake,” said Pflug.
That policy has come at a cost to City Light. Keeping water in Ross Lake has meant that less power than normal was generated at the three dams below the reservoir, causing City Light to purchase more high-priced market electricity.
But maintaining adequate water in Ross Lake is crucial, for a number of reasons:
City Light’s federal license for its Skagit dams requires certain minimum flows for different times of the year. Under drought conditions, City Light can alter those flows, with approval from the Skagit Flow Coordinating Committee. The chart below shows how the new flows, as measured in cubic feet per second at Newhalem, would differ from current required minimums.
- The cost of market electricity is expected to soar even higher this summer. If Ross Lake is low, City Light’s power costs could be even greater than they were this winter. If the region’s drought extends into next fall and winter, entering that period with a depleted reservoir could spell financial disaster for the utility.
- A depleted reservoir would also spell trouble for fish. In winter, nests require adequate flows for protection. In summer and fall, fish need adequate flows to spawn. On the Upper Skagit, those flows come from Ross Lake, especially when drought affects natural flows.
Under this plan, Ross Lake would gradually refill from an estimated elevation of 1,531.3 feet above sea level at the end of April. Full pool is 1,602.4.
For more information, contact any of the following members of the Skagit Flow Coordinating Committee:
- Steve Fransen, fisheries biologist, National Marine Fisheries Service, 360.753.9440
- Dave Pflug, fisheries biologist, Seattle City Light, 206.386.4574
- Gary Sprague, Washington Department of Fish and Wildlife, 360.902.2539
- Stan Walsh, Skagit System Cooperative, 360.466.1512