For the week of October 2 - 8, 2002

Winter precipitation outlook not good

Water manager antsy over empty reservoirs

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By GREG STAHL
Express Staff Writer

A recently released weather outlook shows Idaho is expected to get below normal precipitation this fall. For water managers and skiers alike, that raises red flags.

Following two below-average years, water users across the southern three-fourths of the state have been crossing their fingers and hoping for banner snows this winter. Without at least a good snow year, irrigators of more than 3 million acres of croplands may face one of the hardest growing seasons on record, Idaho Department of Water Resources spokesman Dick Larsen said.

But a Sept. 25 report from the National Weather Service indicates that Idaho and the Northwest could face extremely dry conditions.

"The best chances for overall drought improvement extend across the Southwest and the Great Plains, but the odds tilt toward minimal relief for water shortages in the Northwest, northern Rockies, and Great Basin, with even a good chance for drought expansion in the Northwest," according to the report.

"A large portion of the Northwest is expected to see below-normal precipitation during the October (through) December period," the report continued. "Although below-normal rain and snow would not have significant immediate impacts, deficient snowpack could have adverse impacts later."

Additionally, according to the National Oceanic and Atmospheric Administration’s Climate Prediction Center, Idaho precipitation is predicted to be zero percent to 10 percent less than average each month through March.

A building Pacific El Nino pattern is largely responsible. El Nino occurs as a result of a periodic warming of surface ocean waters in the eastern tropical Pacific. El Nino affects weather around the globe, and episodes occur roughly every four to five years, lasting up to 18 months.

Larson said this year’s reservoir carryover is almost nonexistent, except for the Payette River drainage in west central Idaho, where Cascade Reservoir is 58 percent full and Deadwood Reservoir is 33 percent full.

"We didn’t have any extra water going into this year, and it’s taken everything we’ve had just to get by," Larson said. "We’re right back where we were last year, needing far above average snowfall."

The water carryover picture gets worse farther to the east.

The Upper Snake River system, including Jackson Lake, Grassy Lake, Lake Walcott and Palisades, Island Park, Ririe and American Falls reservoirs, was at 15 percent of capacity last week. American Falls, one of the largest reservoirs in the system, is only 3 percent of capacity, and Palisades, another of the largest reservoirs, is only 7 percent of capacity.

"It’s getting pretty desperate in Eastern Idaho," where the state has received increasing reports of illegal water diversions, Larson said.

The Boise River system, including Anderson Ranch, Arrowrock and Lucky Peak reservoirs, was at 56 percent of capacity.

Another problem is that next year’s irrigation season follows several seasons of drought, so underground water levels, which take several years to recharge, are expected to retreat further.

Gov. Dirk Kempthorne declared drought emergencies in 15 counties this summer.

"The bank is absolutely empty," Larsen said. "We’re completely dependent on what we make in snowpack."

 

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