Environment

Idaho water supply isn’t in crisis yet, but what about next year?

In this 2015 photo, the snow is nearly gone on the Trinity Mountains in the Boise National Forest. With more back-to-back low snow years Treasure Valley’s “fourth reservoir” – as farmers call the snowpack – is going to provide far less water into the future, forcing farmers to depend more on the Boise River’s Anderson Ranch, Arrowrock and Lucky Peak reservoirs.
In this 2015 photo, the snow is nearly gone on the Trinity Mountains in the Boise National Forest. With more back-to-back low snow years Treasure Valley’s “fourth reservoir” – as farmers call the snowpack – is going to provide far less water into the future, forcing farmers to depend more on the Boise River’s Anderson Ranch, Arrowrock and Lucky Peak reservoirs. Bureau of Reclamation

Ron Abramovich usually dons snowshoes to walk through 3 feet of snow and more to measure the season-ending snowpack at 6,100-foot-high More’s Creek Summit east of Idaho City.

The trek to the measuring site this year was over scant snow. Abramovich, in his snowshoes, had to climb over fallen branches, across flowing streams and over dry topsoil.

“It looked like June 1 instead of May 1,” said Abramovich, water supply specialist for the U.S. Conservation Service.

He measured 14 inches of snow, with a water content of 5.9 inches, among the lowest totals since agencies began measuring in 1940. Only the drought years of 1977, ’87 and ’92 were worse.

Most of Idaho is now in a drought, according to federal agencies. But only far Southern Idaho is suffering to the degree that California and other states are. California is in its fourth year of drought, with reservoirs and river flows low and state officials declaring a crisis that touches the lives of nearly every resident.

But in Idaho, most residents and even farmers will feel only minor effects this year, despite an unusually low snowpack and early runoff. That’s because last year most of the state had a higher-than-average snowpack and reservoirs ended the year full enough to carry most farmers through the 2015 growing season.

Still, Idaho Power Co., which generates its cheapest power from hydroelectric dams, will have to go more often to more expensive sources of electricity.

“It’s going to be a tight year,” said Kresta Davis-Butts, an Idaho Power hydrologist.

If it stays dry and the snowpack next winter doesn’t refill the reservoirs, Idaho’s water situation could take a turn for the worse. Already this year, senior water users in the Magic Valley, who get their water directly from rivers or springs, have demanded that users who get their water by pumping it from the ground give them 89,000 acre-feet of water or leave some lands idle.

DISAPPOINTING END TO WINTER

Idaho started the winter with a promising snowpack throughout the Upper Snake River Valley west to the Boise Basin. But a band of unusually warm Pacific waters from Mexico to Canada that was bringing almost no snowpack to California, Oregon and Washington spread to Southern Idaho.

Last year a “blob” of warm water, as scientists called it, showed up off the coast of Alaska. This year, the entire Pacific Coast has turned warm, with Seattle 6 degrees above average. Lower snowpack is a continuation of a trend that climate scientists say they have seen for several decades in the Pacific Northwest.

By March, nearly all of Idaho was feeling the effect of the warm, dry winter. Southern Idaho’s snowpack peaked, with lower- to middle-elevation snowpacks melting and runoff beginning early. By April, Treasure Valley farmers were scrambling to adjust to conditions even though levels at Anderson Ranch, Arrowrock and Lucky Peak reservoirs are 80 percent to 93 percent of average.

“I refer to the snowpack as our fourth reservoir,” said Rex Barrie, Water District 63 watermaster in Star, the man who ensures that water goes to the right users. “It’s only at 40 percent of average.”

And it’s worse as you move south. The Bruneau River watershed has had the lowest three-year period of precipitation since 1944. This year will be its fourth year of drought. To the west, Owyhee Reservoir is at only 26 percent full, with most of its runoff done.

The same weather pattern that carried the dry conditions from California to the Bruneau reaches up to Idaho’s Wood River and Lost River basins, Abramovich said. Luckily, watersheds along the Continental Divide, such as the Salmon and Clearwater, caught some of the snowstorms that came out of Canada and covered Montana and points east.

GROUNDWATER COMPOUNDS PROBLEM

What sets this drought apart from 1992 and before is what water managers now know about the aquifer. Levels have dropped an average of 200,000 acre-feet annually in the Eastern Snake River Plain Aquifer, a Lake Erie-sized underground reservoir that stretches from Ashton in the east to King Hill near Glenns Ferry. Those levels peaked in the 1950s, dropping since in part due to changes from flood irrigation to sprinklers — which seep less water back into the aquifer — and to the rise in groundwater pumping for farming.

The drop in flows can be seen on the Snake River at Murphy, just below Swan Falls Dam. A 1980s agreement between Idaho and Idaho Power set minimum stream flows for power at 3,900 cubic feet per second during irrigation season and 5,600 cfs in the winter.

The winter flows dropped below the minimum for one day this year. Flows skate near the summer minimum nearly every year, said Brian Patten, chief of the Idaho Department of Water Resources Planning Bureau.

To combat this drop, the Idaho Water Board began full-scale operations to recharge the aquifer, sending water down several canals this winter so it would seep into the groundwater. The state was able to put 75,000 acre-feet back into the aquifer.

Eventually it hopes to put as much as 250,000 acre-feet into the aquifer, to rebuild the natural spring flows that help fill the Snake. But Idaho might one day be forced to dry up acres of farmland that have the most junior water rights to meet the demands of those with more senior rights.

In April, Magic Valley canal companies and the farmers they serve demanded 89,000 acre-feet of water to make up for the loss they say was caused by groundwater pumping, which reduced spring flows into the Snake River from Blackfoot to the Minidoka Dam. Groundwater users are negotiating in hopes of reaching a long term agreement.

The minimum flows, the recharge, and the management between surface and groundwater users in Idaho that came out of a 27-year adjudication of water rights in Idaho give the state a structure to manage water scarcity that California is only beginning to recognize it needs. Patton is hopeful the state can do even more recharge.

“We still have a lot of work to do in the future,” Patton said. “But this was a good start.”

Meanwhile, Idaho farmers, boaters, anglers and others can be grateful that Idaho is not yet facing the economy-reshaping drought that California’s dry spell portends.

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