Snake River's Eight-Reservoir Systemby John O'Connell, Journal Writer
POCATELLO - We're dry. The Snake River's eight-reservoir system measured lower Oct. 11 than at any other time in its history.
The system was at 9 percent of capacity with a combined 385,000 acre feet of water, evidence southeast Idaho's prolonged drought has consumed most reserves.
The reservoirs have made modest gains since the record low measurement, increasing to 14.6 percent full as of Monday.
Experts say if the area gets at least an average snowfall this winter, farmers and ranchers could make it through another summer, although there would not be any water carryover for the next year.
The worst case scenario isn't pretty.
"There is no water in the bank, the reservoirs are empty, and we don't have anything on the horizon to say we're going to have a huge snow year," said Idaho Department of Water Resources spokesman Dick Larsen. "If the situation is as bad as we think it is and if it gets even worse, you're going to see a lot of farms, particularly smaller farms, going under."
The reservoir system's previous record low was 1977, a benchmark year for droughts when the reservoirs had 386,000 acre feet.
"The real question is, is this as bad as it's going to get?" Larsen said. "We don't know if we are in a 10-year drought, only three years into it, or going into the fourth year of a four-year drought."
Groundwater has also been impacted. Larsen said last year, his office received a record 2,000 requests in southern and eastern Idaho from people wanting to dig new wells or deepen existing wells.
For three consecutive years, snowpack between Pocatello and Island Park has been 70 to 80 percent of normal, Watermaster Ron Carlson said. During each of those years, eastern Idaho supplemented the difference with reserves from the reservoirs.
Twelve of the past 16 years have also been drought years, Carlson said.
If there is no precipitation at all this winter, the reservoirs will be one-third full by spring with river water, Carlson said.
"I deliver on an average year 8 million acre feet of water. A third (capacity in the reservoirs) represents 1.5 million. That's not uniformly distributed. A lot of canals couldn't turn on," Carlson said. "If this is a dry winter, we're going to have the toughest year next year we've ever had. We will see production hits throughout the Upper Snake."
A normal winter could fill the reservoirs, with fast springtime melting conditions, or significantly raise the level of the Snake River with a slow springtime melt.
The Snake River also set an all-time record low in August. The measurement was taken at a river gauge near Heise.
This winter, the region will not be impacted by El Nino, a disruption in the ocean-atmosphere system in the tropical Pacific which has forced moisture away from Pocatello in recent years.
Carlson said the area has an equal chance at having a good or bad snow year, but meteorologists see no signs that it will be an exceptional winter.
"We're out of assets right now, but if we get to normal, we've learned to live on that," Carlson said. "It doesn't mean we have surpluses, but it means you get by."
Chris Ketchum, deputy area manager for the Bureau of Reclamation, said last week his office reduced water flow below the Palisades Dam to 950 cubic feet per second and will remain at that level until spring.
The reason for the reduction is two-fold - it saves water, but new data also suggest lower winter water flows favor native cutthroat trout over rainbow trout.
Idaho Department of Fish and Game officials are managing the river to restore it as a native cutthroat fishery.
"We have been lower than this in the past, so it's not like we don't have precedents," Ketchum said, adding experts previously thought more water flow in the winter was better for fish in general.
Water levels have also been significantly reduced below the American Falls Reservoir, which is now passing a trickle of about 350 cubic feet per second.
"That's not very much water. That's probably about the minimum they believe would support fisheries," Larsen said. "The trick is you don't want to destroy fisheries in the process of trying to save water."
He said water flows were shut off completely below the Island Park, Grassy Lake, Ririe and Henry's Lake reservoirs.
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