Forecast: Water supplies across Oregon mixed

PORTLAND — Oregon farmers and ranchers can expect mixed irrigation supplies heading into summer after months of fast-changing weather.

The USDA Natural Resources Conservation Service released its statewide water outlook report for May, predicting near- to above-average stream flows in eastern and southern Oregon, and near- to below-average stream flows in central and western Oregon.

Scott Oviatt, snow survey supervisor for the NRCS in Portland, said reservoir levels are faring well across the state, averaging from 93% to 140% of normal storage.

“Water users that have access to reservoir storage will likely have adequate water supplies this summer, while those dependent upon in-stream flows will need to continually monitor conditions due to rapidly changing weather patterns,” Oviatt said.

Conditions have been feast or famine through most of the water year dating back to October, Oviatt said. The year got off to a slow start until record-breaking snowfall in February, which dramatically changed the agency’s forecast.

Then came early April, bringing heavy rains that mixed with rapid snowmelt to cause widespread flooding and record-high stream flows. More than half of river gauging stations around the state measured record-high stream flows, including 300% to 500% of normal in the Umatilla, Walla Walla and Willow Creek basins of northeast Oregon.

Flooding also occurred in the Willamette Basin, which received 186% of its normal April precipitation. Now, as temperatures rise into the upper 80s and much of the in-stream flow has already passed, Oviatt said the concern will begin shifting toward parched rangeland and the possibility of wildfires.

Overall, basins in eastern and southern Oregon have received 100% to 120% of normal precipitation dating back to October, while those in western and central Oregon have received 85% to 100%.

Snowpack continues to linger at higher elevations in Eastern Oregon, while dwindling to about half of normal in the Klamath, Willamette and Upper Deschutes basins, and as low as 40% in the Hood, Sandy and Lower Deschutes basins.

Thanks to a wet February and April, the U.S. Drought Monitor lists just 17% of Oregon as “abnormally dry,” as opposed to 81% of the state a year ago.

That said, the National Climate Prediction Center is calling for increased chances of higher temperatures and a roughly equal chance of above- or below normal precipitation over the next three months.

“In an optimum world, we would cool down here and still get some spring precipitation carrying through the early part of June,” Oviatt said.  “As we know, by that point in time, we just don’t receive that much precipitation after that.”