Dam regulators try to maintain minimum flows

Dam regulators in the Willamette Valley are trying to maintain minimum flows in the Willamette River even while reservoirs have less water than usual.

The Willamette at Albany was about 4,570 cubic feet per second Wednesday, about 200 cfs less than a long-term average for this time of year.

“The flow in August and September should be 5,000 cfs, but we are working with the state Department of Environmental Quality to adjust the release to 4,500 cfs,” said Mary Karen Scullion, a Corps of Engineers hydrologist in Portland. “That seems to be an adequate flow to maintain water quality, yet allow us to retain more water in the reservoirs.”

Jared Reubin of the DEQ’s Eugene office, said there have been no health issues reported in the Willamette’s mid-valley section.

“There have been no algae blooms or abnormally high loads of bacteria that we’re aware of,” Reubin said. “We’re not aware of any monitoring data coming in that show any variations outside of normal.”

A drier than normal spring has had an effect on the reservoirs in the Willamette Basin, according to projects manager Erik Petersen, based in Lowell.

“The rivers are fine because we have statutory requirements to maintain certain inflows,” Petersen said. “Where we’re low is in the reservoirs themselves.

“Overall, our system storage is about 60 percent of normal. Last year was a good water year in terms of storage, but this year, we didn’t get the rain in May that we needed.”

Amy Echols, a Corps public affairs spokeswoman in Salem, said the Willamette Valley project reservoirs are filled primarily by rainfall, not winter snowpack.

“The snowpack was only about 54 percent of normal in May and rainfall was about 64 percent of normal. We’re definitely on the lower side in terms of precipitation,” she said.

The flow in the Willamette comes from several of the dams, depending somewhat on fish runs and time of year, Echols said. Representatives from several government agencies and water resource groups meet weekly to discuss water needs and water flow issues.

Water from the dams was used in the spring to help support the migration of salmon into the rivers, but the usual rains did not appear to help replenish water supplies.

Tuesday, the average inflow of water into Green Peter Reservoir was 138 cfs while outflow was 673 cfs. Foster’s inflow was 778 cfs and outflow was 800cfs. Detroit was taking in 790cfs and releasing 1,000cfs.

The public can keep track of current water levels in Willamette Valley reservoirs online at www.nwp.usace.army.mil/pa/river.asp.

Alex Paul can be reached at alex.paul@lee.net or 812-6076.