Even after the largest water flow event at the Ballard Locks in recorded history, the operation to refill Lake Washington starts tomorrow, Feb. 15.

The peak inflow rate was at its highest from Feb. 7 to 9, recorded at between 15,000 and 16,000 cubic feet per second (average flow is 13,700 cfs). With the huge amount of water moving through the Ship Canal, water managers at the Locks were releasing 13,500 cfs from the spillway, the maximum spill capacity for the current lake level.

“Detailed record keeping began in 1946,” Seattle District Hydrology Section Chief Ken Brettmann said in a statement about the refill operations. “Essentially, this is the largest inflow event since World War II.”

The typical annual refill will bring the lake to an elevation of 22 feet, which is enough to meet increased summer water use, which the Army Corps says will provide water necessary for fish passage, navigation, and salinity control

The Army Corps says that during the refill, vessel owners should closely monitor lake elevations and adjust mooring lines as necessary. Those who live or do business along the Ship Canal or in Lakes Washington and Union should expect a gradual rise from the winter level of 20 feet to the 22-foot target by June 1.

If this all sounds fascinating and you want to keep updated on the Lake Washington water status, you can follow along on the Corps’ Seattle District Reservoir Control Center website.

Photo by Jerry Simmons