Friday — May 7, 2004

Promising water year turns bleaker

Mountain snowpack foretells desert drought

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By MATT FURBER
Express Staff Writer

Quickly dissipating in Idaho’s snowpack is the history of winter weather and clues to the future of summer water.

Natural Resource Conservation Service forecasters Ron Abramowich and Tom Perkins—whose job it is to manage automated snow data collection sites known as SNOTEL sites—have been busy collecting data to predict stream flows down valley.

Things do not look good for plants and wildlife. Snow in the mountains, the source of late summer water, is drying up.

Perkins and Abramowich met last week at the Morse Creek measuring station north of Idaho City to for on site confirmation of automated data beamed to NRCS headquarters.

Data about snow depth, moisture content and mountain temperatures can be used to calculate how much, how fast and when water will flow out of the mountains.

"I try to forecast what’s going on sitting in front of a computer," said Perkins, who forecasts for the entire Columbia River Basin. "In a dry year, sometimes Canada can carry us."

This year even that contingency is remote, he said.

Perkins said it is important to get in the field to see what’s going on.

For example, at one SNOTEL site the water content values of the snow were changing from day to night.

"We think we had a bear sleeping on the snow pillow (where the weight of the snow pack is measured) after he vandalized the site," Abramowich said.

Data show that the Morse Creek SNOTEL site had one of the best snowpacks in the Boise basin on April 29. The reading was 69 percent of average for water stored in the snow pack.

Abramowich from Boise deciphers what the snow pack will provide to Idaho rivers, including the Big Wood River.

"During the heart of the heat spell in late May last year, we were losing one and a half to two inches of snow water a day," Abramowich said. "When you’re losing water that quickly the ground can’t absorb the water."

This year the snow is melting at less than one inch a day with a lot going in the ground, he said.

Abramowich explained that although the region is in another drought year, the dynamics of runoff compared to last year show two extremes.

For example, the Big Wood River crested on Memorial Day in 2003. This year the river could peak in the next one to two weeks, a month ahead of schedule, he said.

"If we had had two more days of high runoff last year there would have been more flooding," Abramowich said.

Last year the snowpack was 85 percent of average for the Big Wood River basin. But this year by May 1 it was already down to 50 percent of average. A delayed melt last year produced a fast runoff and low stream flows later in the summer. Low snow water content this year and moderate temperatures this spring will keep stream flow peaks low and bring drought conditions later this summer.

University of Washington climatologist Philip Mote, with the Climate Impacts Group at Center for Science in the Earth System in Seattle, presented a paper at the annual Western Snow Conference in Vancouver, B.C., in April that blames warming trends for the current drought.

An article in the Feb. 20 issue of Science Magazine titled "As the West Goes Dry" also summarizes Mote’s paper. It describes the dynamics of the warming trend as it is related to Pacific Ocean weather patterns and increases in greenhouse gases. Mote’s paper theorizes that historical snow pack data and models of future climate change do correlate, and water problems in the West will continue to increase.

The trend is confirmed by data collected with the numerous instruments at hundreds of SNOTEL sites in the West.

On Wednesday, Idaho Gov. Dirk Kempthorne issued a drought emergency declaration for Fremont County. On Thursday, he added Custer and Lemhi counties to the list for a total of seven counties currently under the declaration. Others include Butte, Caribou, Clark and Lincoln counties. Lincoln comprises the lower Big Wood River

"Each basin is unique in how it feeds ground water and stream flows," Abramowich said. But, what started as a promising year now looks bleak throughout the region, he said. "Even with above average precipitation it will take two years to prime the system before we see average surface flows."

"It is becoming ever clearer that these projected declines in (water stored in the snow pack), which are already well under way, will have profound consequences for water use in a region already contending with the clash between rising demands and increasing allocations of water for endangered fish and wildlife," Mote concludes.

Abramowich and Perkins data was used to support Mote’s thesis.

To show how things can change through the winter Abramowich said precipitation at Morse Creek for the year was 92 percent of average on April 1, but by April 29 it was already down to 87 percent of average.

When March and April precipitation amounts are combined and analyzed against more the than 20 years that NRCS has been collecting dailey precipitation data, 27 out of 70 SNOWTEL sites in Idaho set new record low amounts for the March and April period, Abramowich said. Another 24 sites recorded their second lowest amounts. Many of the SNOTEL sites in Idaho’s central mountains set these new records.

Although cooler temperatures in April have slowed what is left of mountain runoff, Lynn Harmon, manager of the Magic Reservoir Company said irrigation time below the dam on the Big Wood River has been reduced from 90 to 45 days.

Approximately 30 inches of snow water remain at Morse Creek. As Abramowich sampled plugs of snow at the site to check for data collection accuracy, he said an indication of the serious drought condition is the moisture of the soil.

The dirt was not wet enough to pack. Water is being absorbed into the ground. Water is not flowing out of the minimal snow pack fast enough to create large stream flows this year without more precipitation. According to NRCS data collected on the Middle Fork of the Salmon River there are snow courses that are melted out now and zero percent of average.

Preliminary May 1 stream flow forecasts for the Big Wood River at Hailey call for only 39 percent of average runoff for the period of May through July and 37 percent of average on the Middle Fork of the Salmon River.

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