Permanently connecting the Big Wood River to Magic Reservoir south of Bellevue could result in an influx of brown trout and a dramatic alteration of the prized rainbow trout fishery, according to Bill Mason, owner of Bill Mason Outfitters in Sun Valley.
"I'm the last guy to stop any stream restoration projects, but this could change the whole complexity of the fishery. Browns could take it over," Mason said. "We might want to be a little more careful about what we wish for."
Mason is referring to an ongoing effort to restore flows to a seasonally dry 12-mile stretch of the Big Wood River south of Bellevue. Known as the Wood River Legacy Project and spearheaded by Rich McIntyre, of Hailey, the seemingly improbable undertaking is gaining support in Blaine County and down-basin communities, and could eventually serve as a pilot project to change Idaho's water laws, which are considered by some to be archaic.
McIntyre wants people to be able to voluntarily keep some of their water in-stream. Current state laws force water right holders to take all of their water or none, a policy that has earned the moniker, "Use it or lose it."
He believes the change in law will benefit farmers and anglers alike because more water will be kept in-stream—or in the aquifer. The Big Wood River below Glendale Bridge is dammed off every summer to redirect water for agricultural purposes. This year, McIntyre estimated, thousands of trout were killed when the river was diverted.
While he's garnered conceptual support for his project from Blaine, Lincoln, Jerome and Gooding counties, as well as the Big Wood and Northside Canal companies, he acknowledged that some people in the agricultural community remain skeptical.
"Whenever you start talking about water, people in the agricultural community get very goosey, and that's understandable since their lives depend on it," McIntyre said.
But he added that he thinks the concerns are based on misunderstandings, which he hopes to clarify in a public meeting in Hailey in mid-September.
Mason said he first heard about the Legacy Project earlier this month while attending the gigantic Outdoor Retailer show in Salt Lake City.
"I was approached by Andy Munter, and he said 'We'd like to get you involved,'" Mason said.
Munter is the board president of Idaho Rivers United, one of the project's primary sponsors.
Later that night, "I was sitting in my hotel room having a cocktail when suddenly it was like someone hit me over the head with a baseball bat," Mason said. "I thought, 'Oh my God.'"
Native to Europe, brown trout were introduced to the United States in 1883. They are highly piscivorous—the diet of an adult brown consists largely of other fish—and more resilient than rainbows. They're able to withstand higher temperatures and degraded water.
"They're also much harder to catch," Mason said.
Browns were eventually introduced to the Little Wood River drainage in the early 1970s and to Magic Reservoir a short time later. In autumn the large fish—browns can grow up to 35 pounds—swim out of Magic Reservoir into the Big Wood River south of Bellevue to spawn.
Mason said once the fish were introduced to the Little Wood River it took them about 10 years to infiltrate the Silver Creek system. He said they now outnumber rainbows four-to-one in the legendary fishery near Picabo.
"We have sampled small regions where rainbows are dominated by brown trout, mainly downstream from Kilpatrick Pond," said Doug Megargle, fishery manager for Idaho Department of Fish and Game's Magic Valley Region. "But it's kind of a catch-22 because in Silver Creek neither rainbows nor browns are native, as far as genetics go. Since neither are native, neither has a priority, unless the people demand it."
McIntyre said he understands Mason's concerns, but he doesn't believe browns will take over the Big Wood River fishery.
"There will be some predation on rainbow trout by browns, but my guess is that it will mainly be in the lower Big Wood River," said McIntrye, a renowned stream restoration specialist. "Fish and Game has stated that the largest limiting factor of the fishery is the disconnect.
"If the river is reconnected to Magic, we will have more and bigger rainbow trout in the river."
Fish and Game's Megargle agreed.
"Brown trout tend to occupy habitat lower in a stream drainage, not just due to temperatures, but habitat. They thrive in deep, scoured, murky holes with slower moving water," Megargle said.
He added that restoring flows and natural conditions to 12 miles of the Big Wood River would actually benefit rainbows and discourage an upstream brown trout migration.
"My impression of the Legacy Project is that they want to restore the river to a more natural state," Megargle said. "Returning a more freestone environment to the river would likely be less suitable to brown trout."
Overall, Megargle said the project's benefits far outweigh its negatives.
"I support any project that tries to protect the natural function of a stream, reduce urban encroachment and enhance or protect a stream," he said. "I believe a project like this, given Blaine County's growth, is well-timed."