Tacoma Power is increasing the rate of river discharge from the LaGrande Dam, from about 2,450 cubic feet per second (cfs) to a projected 7,450 cfs, as rainy weather is expected to continue over the next few days.
The increase in waterflow is not expected to enter the lower Nisqually River into minor flooding zones when the river crests Wednesday afternoon at 8 feet. Minor flooding, according to the National Weather Service, is recorded at 10 feet.
The Puget Sound region on Monday was under a flood watch, which means that conditions are favorable for possible flooding.
“This flow will be maintained depending on weather forecast and could change,” Thurston County Emergency Management wrote on Facebook on Monday afternoon. “Farm and pasture land may experience erosion.”
Residents should prepare to take action at a moment’s notice, the county department said, as river conditions can change rapidly.
Over the last week, discharge at the Nisqually River Hydroelectric project has remained relatively steady, though Tacoma Power, the utility provider overseeing operation of the project, began rapid-releasing water Sunday night.
As of about noon on Monday, the utility was releasing somewhere around 4,500 cfs of water and gaining, according to the National Weather Service. Inflows at Alder Reservoir, meaning the amount of water coming in, is currently at 1,169 cfs and is expected to crest Wednesday afternoon at 17,169 cfs due to rainfall.
The lower Nisqually Delta last February experienced overwhelming flooding that led to widespread damage of dozens of homes.
This story will be updated.