Wednesday, January 2, 2013

Reservoir drawdown highlights water conflict

Irrigators worried about crops, conservationists worried about fish

Express Staff Writer

Irrigation is the life blood for thousands of acres of cropland in southern Idaho. But sometimes irrigation needs come into conflict with conservation needs, especially when it concerns fish. Courtesy photo

Farmers and fish both need water, and sometimes agriculture and conservation needs come into conflict, as was seen this fall when a rapid drawdown was required at Magic Reservoir in southern Blaine County.

The drawdown, needed so that dry repairs could be made on a leaky hydraulic oil line at the Magic Dam hydroelectric plant, is now complete and the reservoir is slowly refilling. But the Big Wood Canal Co., which holds water rights for irrigation from reserves held in the reservoir, is worried about having enough water for its shareholders for the 2013 crop season.

With the reservoir level currently at less than 10 percent capacity, the canal company is retaining every bit of water that it can, and the small flow below the reservoir comes from dam seepage and small springs in the area.

Conservationists were already worried that the rapid drawdown may have damaged the popular fishery in the Big Wood River below the dam, and with only a small stream flow of 5.44 cubic feet per second, as reported Friday by the U.S. Geological Survey, they’re are also concerned that the low flow may further jeopardize the wild trout population below the dam.

Both irrigators and fish will benefit from the abundant snowfall so far this winter, leading to abundant runoff in the spring. As the dam refills, the water pressure will rise, increasing both seepage and spring releases below the dam and thus increasing stream flow.

But while irrigators and conservationists agree on that point, they sometimes don’t agree on the best way to manage water released from the reservoir.

Scott Boettger, executive director of the Hailey-based Wood River Land Trust, noted that water retains more oxygen when temperatures are lower, but said an increased flow below the reservoir of even an additional 10 cfs would benefit the fish.

“All you have to do is add some water and they can come back,” he said. “We just need some consistent flows in the off season.”

In the 100-year history of Magic Reservoir, the Big Wood River has experienced dramatic fluctuations in stream flow, sometimes raging during high water years when the reservoir won’t hold all the water coming in and sometimes being reduced to a trickle in dry years when water is held for irrigation.

Through it all, the fishery below the reservoir has survived and even thrived.

Boettger and other conservationists were concerned this fall that the large water releases needed for repairs at the dam would wash fish downstream where they would be stranded and die when the releases were finished.

Doug Megargle, regional fisheries manager for the Idaho Department of Fish and Game, acknowledged that some fish may perish from the releases, but he expects that the fishery will rebound.

“I don’t really know what to expect after what we saw,” Megargle said. “But fish can survive through high water flows. They just hunker down. They find places where they’re not constantly swimming against the current.”

There are some large holes in the Big Wood River below Magic Reservoir and Megargle said that as long as there is some stream flow going into those holes, then the fish have a good chance of surviving.

Boettger said he’s been frustrated in the past trying to work with the canal company, but he’s willing to try again to work out an arrangement that takes into account both the fishery and irrigation needs.

“The good fight is not over—it’s going to just take more creative ideas,” he said. “There are no easy answers. We need to work together to find a win-win for everybody.

“It’s too wonderful of a fishery. We did fish counts down there a few years ago and there were 4,400 fish per mile, more than twice the density of Silver Creek. It’s all on public land and it’s difficult to get to. People don’t know how good it is.”


Big Wood Canal Co.

Carl Pendleton, a Shoshone resident and board chair of the Big Wood Canal Co., acknowledged that some fish may have been lost as a result of the reservoir drawdown.

“Did we move a lot of fish out of there? I don’t know,” Pendleton said. “Normally we try to be mindful of the fishery, but we have to make irrigation our highest priority.”

The Big Wood Canal Co. manages the Richfield Canal, which starts at a diversion dam on the Big Wood River about three miles below the reservoir. The canal runs about 40 miles through Lincoln County but has another 100 miles of laterals that feed off of it.

The Richfield Canal provides gravity flow and sprinkler irrigation to about 35,000 acres of cropland in the Richfield, Dietrich and Shoshone areas, where farmers grow alfalfa and grass hay for livestock, as well as barley, wheat, potatoes and sugar beets.

Pendleton said the canal company is willing to work with the Department of Fish and Game and conservationists to find solutions for best management of the resource, but that the company has to be mindful first of irrigation.

“We’re open to talk to them, but we’ve got to somehow do it on terms that are agreeable to our shareholders because they have to farm to feed their families,” Pendleton said. “We all like to fish, but we have to survive first.”

Terry Smith:


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