U.S. Army Corps of Engineers Seattle District water managers took over regulating flows at five dams to reduce downstream flood risk over the weekend, including the Wynoochee Dam north of Montesano.

“Seattle District’s Reservoir Control Center worked 24-hour operations over the weekend to monitor and regulate Howard Hanson, Mud Mountain, Upper Baker, Ross and Wynoochee dams,” said Western Washington Senior Water Manager Jon Moen.

The City of Aberdeen owns the Wynoochee Dam, although it is operated by Tacoma Public Utilities for power production.

The Corps began regulating the Wynoochee Dam early Saturday, Feb. 1. During peak operations the inflows to the dam were above 8,000 cubic feet per second and Corps water managers were holding back nearly that entire amount, releasing only 200 cubic feet per second. Corps officials returned control of the dam to Tacoma Public Utilities Monday afternoon.

The Corps owns and operates Howard Hanson and Mud Mountain dams and directs operations of the utility-owned projects during flood events per established agreements. According to the Corps, “Public Law 84-99 enables the Corps to assist state and local authorities in flood fight activities and cost share in the repair of flood protection structures. The purpose is to prevent loss of life and minimize property damage associated with severe weather.”

In the Skagit River basin, the Corps took control of the Upper Baker and Ross dams early Feb. 1. During peak inflows, Corps officials held back about 19,000 cubic feet per second at both dams.

“Holding back these flows helped reduce downstream Skagit River flows at Concrete, Washington, from about 114,000 cubic feet per second to 78,000. This is equivalent to a river stage reduction at Concrete of over five feet,” said Moen.

Operations were returned to Puget Sound Energy-owned Upper Baker Dam and Seattle City Light-owned Ross Dam February 2.

At Howard Hanson Dam, Green River inflows rose above 10,000 cubic feet per second and Corps water managers held back over 4,000 cubic feet per second during the event’s peak. Mud Mountain Dam inflows for the White River were above 9,500 cubic feet per second and managers targeted releases below 6,000.

“Public safety is our number one priority and our next concern is reducing the reservoir pools,” said Moen. “You’ll continue to see elevated outflows as we reduce pools to make reservoir space as we anticipate potential flooding later this week.”