The population of rainbow trout in the Boise River is healthy today, more than twice what it was a decade ago, said Andy Brunelle, an officer in the local Ted Trueblood chapter of Trout Unlimited. That's thanks to higher winter water flows, protection of riparian areas, habitat restoration and fishing regulations, said Brunelle.
The Idaho Department of Fish and Game counts fish in a few sections of the Boise River every three years. In 1994, there were 288 wild rainbow trout in a one-mile stretch. In 2010, there were 5,116.
Brunelle nominated the rainbow, known for its spots and iridescent scales, as a Boise icon.
"You know as well as I, the image of the fly angler standing in the Boise River with the city buildings in the background," said Brunelle.
"It would not be a legitimate image were it not for the trout that have re-established in the past decades after they were pretty much wiped out."
The nadir for trout in the Boise followed the construction of Lucky Peak Dam in the mid-1950s. The dam blocked winter flows from Mores Creek, Brunelle said.
In that era - one that preceded Boise's embrace of its river - pollution also harmed the trout. The river was a dump site for industrial waste and sewer discharges. What little water there was, was dirty.
"The river was in tough shape," said Brunelle.
Establishment of the Greenbelt in the early 1970s, coupled with federal clean water regulations, helped the fish recover.
Agencies including the U.S. Bureau of Reclamation, the U.S. Army Corps of Engineers and Fish and Game also worked to increase winter water levels in the Boise River.
High winter flows mean more shallow side channels where young trout can shelter and grow, as well as bigger breeding grounds for the insects trout eat.
Wild rainbow trout are native to the Boise River and genetically related to steelhead, said Brunelle. The rainbows that live in the Boise River now are a mix of native and hatchery-raised stock that have cross-bred.
Anna Webb: 377-6431