Posted: Thursday, October 04, 2012 12:00 PM
John O'Connell/Capital Press
The American Falls Reservoir, the largest in the Snake River System, is now at about 8 percent of capacity following a hot and dry summer.
Wild swings in precipitation leave reservoirs empty, rangelands parched
By JOHN O'CONNELL
Record books will reflect above-average moisture throughout the Pacific Northwest for the water year that ended Oct. 1.
But coming off an extremely hot and dry summer and heading into a mild El Niño winter that climatologists predict is likely to bring below-average precipitation to the region, water managers remain concerned about the 2013 water outlook.
For the 2011-12 water year that ended Sept. 30, Oregon received 103 percent of its average rainfall, the Idaho mountains had about 101 percent of normal moisture and Washington's precipitation was 108 percent of normal, according to the Natural Resources Conservation Service.
Yet wildfires have charred the region's withering rangeland, massive reservoirs have been drained and dryland growers have seeded winter wheat into dust.
"You almost have to break this last water year into chunks and look at it," said Scott Pattee, water supply specialist with NRCS in Washington.
He explained the season started with a dry fall, followed by a wet, late winter and early spring and ended with a dry summer that hasn't seen more than 25 percent of average precipitation throughout Washington for the past two months.
"When it turned hot and dry, anything that wasn't irrigated burned up. You had lush, green range in mid-July, and by mid-August, you were kicking dry grass stems," Pattee said.
Jon Lea, snow survey supervisor for the NRCS in Portland, describes the regional water year statistics as "skewed," noting a disproportionate amount of moisture fell during the spring.
"When you look at how it works out, it's not that great. Our southern tier counties have been very dry, and Harney, Lake and Klamath counties all had state drought declarations, as well as USDA drought declarations," Lea said.
Much of Idaho and most of California is also covered by disaster declarations to help growers recoup losses from heat, drought and fire.
Northern California ended the water year with just 66 percent of its average moisture. With the exception of the northern coast, Golden State officials reported their first dry year since the 2007-09 drought.
California ranchers were especially hard hit. According to USDA, 85 percent of the state's range and pasture land was in poor or very poor condition as of Sept. 30, compared with 34 percent in Washington, 46 percent in Oregon and 51 percent in Idaho.
Fueled by a dry summer, wildfires have charred forage on 1.5 million acres of Oregon range land, said Lynn Voigt, state director of the Oregon Farm Service Agency. Nonetheless, Voigt considers the Pacific Northwest to be relatively fortunate during a severe drought that's gripped about two-thirds of the contiguous U.S. states.
In southern Idaho, growers are concerned about the lowest carryover since 2007 in the state's major water storage system. Combined, the nine Snake River reservoirs average 28 percent full. American Falls Reservoir, the largest in the system, is at 8.6 percent full and continues to drop. The No. 2 reservoir, Palisades, is 12 percent full.
A poor snowpack this winter could force certain growers to change cropping patterns, said Lyle Swank, watermaster for the Snake River system.
"The reservoir system wasn't built to get us through back-to-back dry years," Swank said.
Reservoirs serving southeast Oregon have also been taxed by a hot and dry summer. The Thief Valley reservoir is empty. Beulah Reservoir is 6 percent full, Warm Springs Reservoir is a quarter full and Phillips and Owyhee reservoirs are both at 32 percent.
California Department of Water Resources officials said they managed to deliver 60 percent of requested State Water Project water, helped by strong storage carryover. The state's 161 reservoirs are now at 58 percent of capacity on average.
"Should the new water year beginning Oct. 1 also be dry, the state's reservoirs and groundwater basins will have less carryover storage for the following year," the department wrote in a press release.
Washington growers are less dependent on stored water, relying heavily on natural moisture in the eastern part of the state and ample river water in the Columbia Basin.
Guy Gregory, technical unit supervisor for the Washington State Department of Ecology in Spokane, said a dry start to the water year last fall stressed dryland winter wheat crops and hurt yields, a situation he sees repeating now.
Eastern Idaho dryland grower Sid Cellan and his neighbors in Caribou County have planted winter wheat in dry soil and are hoping for the best.
"All I can tell you is thank goodness for insurance or a lot of us wouldn't survive," Cellan said.