GRANTS PASS, Ore. (AP) — Oregon's tallest peak has raked enough moisture out of passing storms to claim the only normal snowpack in the state.
But the farther a river basin is from Mount Hood, the worse summertime river flows look.
The latest snowpack maps posted on the Natural Resources Conservation Service show the rangelands of the John Day, Malheur and Owyhee basins in Eastern Oregon particularly parched, with the Klamath, Goose Lake and Harney basins to the south not much better off.
The Rogue and Umpqua basins in southwestern Oregon, and Upper Deschutes and Crooked River basins in Central Oregon are mediocre. The Willamette Basin is near normal.
Like other states across the West, Oregon depends on winter snow in the mountains for the bulk of river flows in summer, when rain is rare. Overall, the state's snowpack was at 84 percent of normal, after troublesome high pressure ridges diverted storms headed this way. They seem to have gone north to Washington, where the overall snowpack was rated at 112 percent of normal. Nevada and Idaho were both worse off. Idaho was 80 percent, and Nevada 64 percent.
The measurements are based on a combination of automatic reporting sites, as well as surveys were crews go out and measure the weight of the water in a core sample of snow.
The forecasts are used by farmers to see how much irrigation water they can expect, utilities to plan for hydroelectric plant outputs, and fisheries managers for conditions facing salmon as they migrate out to sea and back upriver to spawn. Whitewater outfitters also use them to plan their rafting seasons.
NRCS hydrologist Julie Koeberle said the water year started off wet in Oregon, but a dry spell in February and March has left many basins far behind schedule. Warm temperatures in those same months hastened melting, diminishing what was there. The worst off basins are in the southwestern corner of the state, where the Malheur Basin is at 25 percent, and the Owyhee 30 percent.
"It's really rare to have these long dry spells during wintertime, the critical precipitation months for all of the Western United States," she said. "When we have long dry spells, it's really hard to catch up, as far as snowpack is concerned."
The service's latest forecast calls for streamflows to be a little better than current snowpacks. The Deschutes east of the Cascade Range was forecast to have 98 percent of normal flows, which is good news for whitewater rafters. Another whitewater river, The Rogue, was forecast for 88 percent.
Farmers will be looking for rain in the Klamath and Owyhee Basins. Flows into Upper Klamath Lake were forecast to be 61 percent of normal, and flows into Owyhee Reservoir were forecast to be 49 percent.
The Willamette Basin had 92 percent of normal snowpack, the Umatilla 67 percent, the Grande Ronde 70 percent, and the John Day 44 percent.
Coos Lake was 59 percent, Harney 55 and Upper Deschutes and Crooked 76 percent. The lower Deschutes, Sandy and Hood River basins were at 101 percent.
On the Web: Natural Resources Conservation Service: http://www.or.nrcs.usda.gov/snow/
Copyright 2013 The Associated Press.