Among Colorado's sterling tail waters, few would dispute the eminence of the Frying Pan River: 14 miles of gorgeous stream below Reudi Dam, 8 miles of which offer roadside public access. It's fishable all the way up to the concrete foot of the dam, which isn't permitted on most other tail waters. And it stays ice-free in its upper reaches because of the 40-degree currents that issue from the dam.

Trout keep right on feeding, oblivious to the season. Slate gray dippers, water ouzels, twitter and wade into the stream to feed on an aquatic smorgasbord unmatched almost anywhere else in Colorado.

The problem in summer is that anglers often must stand in line for preferred fishing beats. But in winter, particularly in an icy gale, an angler can march right up to that hallowed spot known indelicately as the Toilet Bowl and yank trout until his arm gives out.

Ben Adams of Pleasant Grove, Utah, did just that. In the howling blizzard, he was the only person fishing the Frying Pan's usually busy upper mile. He stood at the foot of the dam, straight-lining with a Mysis shrimp fly, playing one stout trout after another.

"It's a good spot," Adams said. "I was here last week for the first time. It was so good, I came back."

Although the Frying Pan River is one of Colorado's most beautiful places, nobody can accuse its most famous fishing hole of scenic charm. Water boils from the concrete into a dark pool 40 feet deep. It's like fishing in a noisy bunker. But trout, including a few monsters of 15 pounds, queue up there to munch Mysis shrimp.

The Mysis, a freshwater shrimp introduced from the Great Lakes, has wreaked havoc in many reservoir food chains. But the tiny clear and whitish shrimp have inspired a cult following among fly fishers who angle beneath dams, particularly on the Frying Pan.

The Pan is stuffed with trout food from aquatic worms, scuds and caddis to mayfly and stonefly nymphs. But Mysis that stream from the dam, sometimes en masse, are the tenderloin that grows fat trout.

A few Mysis nearly always trickle from the dam, but the big waves generally come in March. Tim Heng, who manages the Taylor Creek Fly shop in Basalt, said the shrimp, which turn milky white when they die, sometimes can be seen for more than a mile down river from the dam.

"They are mostly dead or in their dying throes when they come out," said Heng, who, like most Frying Pan regulars, is a keen observer of the shrimp and trout that feed on them.

Fly anglers fish Nos. 18 and 20 Mysis imitations as nymphs, mostly with a dead drift, in the Frying Pan's upper reaches. But, Heng said, swimming imitations also work. When the shrimp are dying they swim in spurts, fast at first, then floating away.

"There's a fair number of Mysis coming out now, which normally doesn't happen with low flows," Heng said. "It typically happens when you have high flows."

That might be because drought and water calls downstream have shriveled Reudi Reservoir to a shadow of its former self, causing the shrimp to concentrate near the dam. When full, Reudi can hold 106,000 acre/feet of water, but it now stands at a mere 38,000 acre/feet.

Nevertheless, the Bureau of Reclamation, which operates the dam, has kept water running for the Gold Medal River. Although no official minimum flow has been established for the Frying Pan, Heng said BuRec tries to keep at least 39 cubic feet per second running from Reudi. The flow currently is 44 cfs, low but adequate for fish and fishermen.

And trout, indeed, were feeding in chow lines on Mysis shrimp.

Some fishing guides, Holt included, have taken curiosity about the little shrimp to its extreme limit. He conceded that eating anything uncooked from a river is risky, because there is always a chance of ingesting the parasite giardia. But in the pursuit of knowledge, he has munched Mysis.

"They taste salty," he said. "And when you cook them, they taste . . . well, like shrimp."