SALEM — An unusually dry winter and early spring has given way to weeks of badly needed rain in the Willamette Basin, which is helping to fill reservoirs for the region’s farms and fish.

The U.S. Army Corps of Engineers operates 13 dams in the basin, providing stored water for irrigation, recreation and hydroelectricity, as well as threatened salmon, steelhead and other wildlife.

On average, reservoirs were 81% full as of May 18 — as high as 96% at Green Peter Reservoir on the Middle Santiam River, and as low as 65% at Fern Ridge Reservoir on the Long Tom River.

Spokeswoman Lauren Bennett said that is a significant improvement compared to just two weeks ago. The Corps now expects most reservoirs will fill, though some might not fill completely.

“We’re releasing minimum flows at all of our dams right now so we can store as much water as we can,” Bennett said.

That is especially important now as drought conditions intensify around the basin. According to the U.S. Drought Monitor, more than 97% of Oregon is currently in some stage of drought, with the Willamette Valley largely ranging from “abnormally dry” to “severe drought.”

Since the water year started in October, figures from the National Weather Service show the Portland area is measuring 9.21 inches below normal precipitation through April. The Salem area is 10.85 inches below normal precipitation, and the Eugene area is 10.56 inches below normal precipitation.

However, May has brought some relief with 1.62 inches of rain in the Portland area, 2.37 inches around Salem and 2.05 inches around Eugene.

Brent Stevenson, manager of the Santiam Water Control District in Stayton, Ore., said more rain means higher natural stream flows, allowing the Corps to store as much water as possible behind the dams.

“There has been a little bit of a rebound,” Stevenson said. “We were having a decent weather pattern, so everybody felt those in-stream pieces would be met without the full releases.”

To meet legal requirements under the Endangered Species Act, the Corps must release specific amounts of water from each dam to support threatened and endangered fish. Downstream releases also help maintain water quality and provide irrigation water for farms.

The Santiam Water Control District supplies irrigation water for roughly 800 customers and 17,100 acres of farmland, along with drinking water for the city of Stayton. It gets stored water from Detroit Lake, which is now about 84% full.

“I do believe at this point that we will have a full allocation,” Stevenson said.

Still, Stevenson said he is urging farmers to be wary of drought and do everything possible to use water efficiently. The National Oceanic and Atmospheric Administration’s Climate Prediction Center is calling for a greater chance of above-average temperatures and below-average precipitation over the next three months across the Northwest.

One major concern this year is how quickly snow is melting in the Oregon Cascades, trickling into streams and rivers. The Willamette Basin has just 44% of average snowpack remaining for the year.

While that is helping to boost reservoir levels now, Bennett — the Army Corps spokeswoman — said in a perfect world that would happen later in the summer when it is normally much drier.

“The snowmelt will always help us. It’s just a matter of when,” she said. “It will be good for Memorial Day, but it probably won’t help Labor Day flows.”