Buffalo River fish passage

_{By JIM DE RITO}

Henry's Fork Foundation Conservation Director

Some people may ask what fish passage on the Buffalo River has to do with the rainbow trout on the Ranch. The answer comes down to reconnection to overwintering habitat in the Buffalo River.

The Buffalo River Hydroelectric Project received a new license for operation in 2004. As part of the relicensing process, the Henry's Fork Foundation (HFF) worked with the Caribou-Targhee National Forest, Idaho Department of Fish and Game (IDFG), and Symbiotics, LLC, managers of the project for Fall River Electric, to improve fish passage. Our primary goal for fish passage at the Buffalo River Hydroelectric Project is to increase the number of rainbow trout in the Henry's Fork.

The number of wild rainbow trout in the world-famous fishery of the Henry's Fork is ultimately determined by the amount of overwintering habitat for young-of-theyear rainbow trout. Rainbow trout are hatched in the spring, quickly grow during the summer and fall, reaching a length of about 4 inches, and then have to survive what will be the toughest challenge of their lives, their first winter. If there is little overwintering habitat, few juvenile rainbows survive, and the numbers of fish in the population declines. If more young-of-the-year rainbow trout can overwinter in the Buffalo River, more juveniles may survive and contribute to the numbers of fish in the Henry's Fork.

Fish passage improvements made at the hydroelectric project, located about 220 yards upstream from the Henry's Fork, include a new fish ladder to provide upstream passage for rainbow trout as small as 4 inches; the turbine intake was more finely screened, and the forebay facing of the dam was redone.

Fall River Electric paid for all of these costly improvements. The hydroelectric project now has the best fish passage since it was built in 1936, providing reconnection to about 7 miles of the Buffalo River and many miles of its spring fed tributaries. All this habitat can now be more effectively utilized by juvenile rainbow trout in the winter.

There are basically three ways that young-of-theyear rainbow trout might benefit from improved fish passage and winter habitat in the Buffalo River. Young-of-the-year rainbow trout could move out of the Henry's Fork, spend the winter in the Buffalo River, then return to the Henry's Fork. Offspring from spawning rainbow trout in the Buffalo River could winter in the Buffalo River, then outmigrate to the Henry's Fork; and outmigrating fish are protected from mortality from entrapment in the turbine intake or in the dam face. All these mechanisms involve fish moving upstream into the Buffalo River past the hydroelectric project, then back downstream to the Henry's Fork. Therefore, fish have to successfully migrate both upstream and downstream for fish passage improvements to benefit the Henry's Fork.

Fish are moving upstream through the fish ladder. A fish trap was begun to be operated at the top of the new fish ladder in March 2006. Since that time, more than 25,000 fish have moved up the fish ladder, including thousands of rainbow trout, predominantly juveniles, brook trout, whitefish, suckers, sculpin, and dace. This many fish moving upstream is beyond what anyone expected - the fish ladder is working - including passage of young-of-the-year rainbow trout! However, we do not yet know the number, age, and timing of juvenile rainbow trout moving downstream past the project - this is next step to evaluating the benefits of improved fish passage.

A fish trap for capturing fish moving downstream past the dam is currently being constructed offsite and will be installed at the dam-boarded spillway toward the end of this summer. This trap will capture fish on their way to the Henry's Fork. Evaluating the number, age, and timing of outmigrating juvenile rainbow trout from the Buffalo River provides a measure of the effectiveness of the fish passage improvements and contribution of fish to the Henry's Fork.

The construction and operation of the outmigrant fish trap is a cooperative project of the HFF, Forest Service, IDFG, Symbiotics, LLC and Fall River Electric. The National Forest Foundation is providing half of the funding for the outmigrant fish trap, with the rest provided by the Ishiyama Foundation, HFF, and Fall River Electric.

For more information on the Buffalo River Hydroelectric fish passage improvements and overwintering habitat for juvenile rainbow trout in the caldera then please visit the Caldera Project link at the bottom of the HFF Web site home page, www.henrysfork.org and navigate to "This week in the caldera."

Also, please visit the HFF blog site for updates on the river or if you'd like to post a question.

This is part of the online edition of Henry's Fork Country.

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