Ocean conditions indicate repeat of La Niña

By JOHN O'CONNELL

Capital Press

Idaho's reservoirs remain so full experts say this winter's snowpack could be 25 percent below normal and still yield an ample water supply for the 2012 irrigation season.

Regardless, the state appears poised to enjoy a consecutive year with moisture levels well above average.

In Idaho, snowpack accounts for 75 percent of annual moisture.

Like last fall, ocean conditions heading into winter are consistent with La Niña -- when cool ocean temperatures along the equator push storms across the Pacific Northwest.

Ron Abramovich, water supply specialist with the Natural Resources Conservation Service, said indicators point to a somewhat weaker La Niña this year.

"Last year was one of the strongest (La Niñas) since the early 1970s," Abramovich said.

Furthermore, precipitation has been well above normal throughout October, saturating soils so the mountains won't absorb snow melt next spring before producing runoff.

Normally, the state begins storing water on Nov. 1.

In mid-September, the state began releasing water below Milner Dam to free reservoir space and will have released 500,000 acre-feet by mid-December, said Lynn Tominaga, executive director of the Idaho Groundwater Appropriators.

The eight reservoirs in the Upper Snake River are now 70 percent full, up 20 percent from a year ago. Bear Lake, which was 36 percent full at this time last year, is now 82 percent full.

"We've never had reservoirs this full this late," Tominaga said.

For the better part of two decades, Idaho Power has released water into Hell's Canyon for the benefit of fall spawning chinook salmon. Roger Fuhrman, manager of water management for the utility, said the 14,000 cubic feet per second Idaho Power released this year was the most in the history of the program.

The good water year played a role in Idaho Power's June 1 rate reduction, which was a 4.72 percent cut for irrigation customers. Looking forward, Fuhrman noted ocean conditions are similar to 1955 and 1956, which were both above average water years.

If snowpack is near normal or better by early next March, Tominaga said the state may release another 500,000 acre-feet for storage space. He was pleased some of this fall's surplus water was put to good use, when Idaho diverted 43,000 acre-feet to recharge the aquifer.

"We're talking with state legislators and others to find out if money can be made available to do recharge this spring," Tominaga said.

Lyle Swank, watermaster over the eastern Snake River Plain, stressed La Niña was also predicted in 2001, but eastern Idaho received a below average snowpack that year.

"Those don't always come through," Swank said, acknowledging an above average year is still "the way to bet right now."

If Mother Nature cooperates, Swank agrees recharging the aquifer should be among Idaho's top priorities.

"I hope we have a lot of water being recharged both this fall and next spring," Swank said. "Big water years don't come around that often."

Recommended for you