On the Colorado River, growing concern for trout and chub

DENVER (AP) — To guide fishing trips for a year or two, that's what brought Terry Gunn to the red canyons of northern Arizona. The chance to hike, raft and fly fish drew Wendy Hanvold, a retired ski bum, who took a job there waiting tables at an anglers lodge. She heard rumors of the intrepid fishing guide who had just returned from an Alaska trip, and one day when he came in approached his table to take his order.

“You fly fish, right?" she said. "I've always wanted to learn."

It was a match made in Marble Canyon.

Since then, the couple opened an anglers shop, guide service, purchased a lodge, and raised their son. They take pride in showing tourists the best spots to catch and release prized rainbow trout beneath craggy cliffs carved by the Colorado River.

But it could all soon change as warmer water temperatures threaten fish survival and the Gunn's livelihood.

Key Colorado River reservoirs Lake Powell and Lake Mead are both only about one-quarter full. The continued drop, due to overuse and an increasingly arid climate, is threatening the fish and the economies built around them.

“We’re in totally uncharted territory,” said Gunn, who began guiding in Marble Canyon in 1983. That year, Glen Canyon Dam began to release water on an emergency basis after record snowmelt produced a powerful spring runoff, resulting in near failure of the dam. In all these years, the river has usually been cold, with typical summer temperatures in the 50s.

But since late August, the water temperature at Lees Ferry — the site of a world-famous trout fishery — has risen above 70 degrees seven times. That might be idyllic for a summer dip under the blazing Arizona summer sun, Gunn said, but approaches peril for the beloved sport fish. A few degrees higher can be lethal.

To make matters...