Printed on: October 03, 2012

Next year critical for reservoirs

By Zach Kyle
zkyle@postregister.com

Despite a near record dry year for eastern Idaho, farmers don't need to worry about irrigation problems next year -- at least not yet.

Reservoir levels in the Upper Snake River Basin received nearly 90 percent of their average inflows this year despite the drought, said Art Hill, civil engineer in the U.S. Bureau of Reclamation's Burley office.

Heavy snowpack from the previous winter helped maintain reservoir levels and kept sprinklers watering crop fields, he said.

However, water storage lags a year behind precipitation because snowpack retains water in mountains above reservoirs. Water availability for the 2013 irrigation season will depend on new snowpack this winter and spring rain, Hill said.

A winter of below-average precipitation would tax the system, he said.

"Even coming out of a bad year, one good year usually replenishes the system," Hill said. "But if we have another dry year like we did this year, it could be a tough irrigation season next year."

Idaho Falls has received 4.32 inches of precipitation through September, according to the National Weather Service. That gives 2012 an outside chance of setting a record-low for rainfall of 5.47 inches set in 2007, Kaiser said.

The city receives an average of roughly 10 inches annually, he said.

Weather Service records date to 1948.

A year of 5 inches below the average isn't a big deal for wet cities such as Seattle, which averages more than 4 inches during three months of the year, or New Orleans, which averages about 8 inches in June alone.

But for Idaho Falls, falling 5 inches short is the chasm between average and poor precipitation years, Kaiser said.

"That's a big difference for here," Kaiser said. "Getting half of what you're supposed to is a significant difference."

The last time Palisades didn't fill to capacity was 2007. Unlike this year, which was just below average for inflow, 2007 was a truly bad water year, when Palisades and American Falls received about 60 percent of their average, Hill said.

Hill was optimistic Palisades would fill again next year.

Weather experts are calling for an El Nino weather cycle for 2013, which could lead to a wet spring that could go a long way toward bolstering the water supply, Hill said.

Back-to-back dry years could mean farmers receive water based on the seniority of their water rights.

Farmers in the Twin Falls area with junior water rights had to shut off their water during a shortage in 2007, a situation that could happen in other parts of the state, Hill said.

"For what happened this year, (water levels) aren't in too bad of shape," he said. "It just depends on what the new snowpack will be."

Zach Kyle can be reached at 542-6746.