WOLF CREEK — Some years ago, a group of college friends and I took a winter trip to fish the Missouri River below Holter Dam. We arrived on a raw February morning and waded into the icy river beneath blue skies. In short order we were into rainbow trout — big, beautiful fish that fought with the vigor of spring.

Before long, fishing conditions deteriorated. A light flurry turned into a raging blizzard. Our guides froze up. Our fingers and toes froze with them. It was frightening how quickly the weather turned.

As we teetered back toward the truck like a motley band of Belgian Echasseurs — our felt-soled wading boots packed high with snow, our rods waving wildly — a form appeared in the gale. Dozens of bighorn sheep crashed through the snow just feet in front of us, seemingly oblivious to our presence, or perhaps just as eager as us to find shelter.

We waited nearly half an hour for the truck’s heater to kick in and thaw the frozen laces of our boots, releasing our feet from that painful grip. In the river below, we imagined the rainbows were still feeding.

Fifteen years later and the trout are still feeding — on scuds and sowbugs and baitfish and midges. The rainbows still rip line off the reel. And the weather can still change in an instant.

“Those rainbows on the Missouri are like little mini steelhead,” said Justin King, owner of Montana Troutfitters in Bozeman. “They will put you in your backing quick.”

Smith grew up in Cascade and has spent many days fishing the Missouri River’s prime trout water between Holter Dam and Craig. He said the Missouri ranks among the state’s best winter fisheries alongside the Madison and Bighorn rivers.

Smith said the Missouri River goes through boom and bust cycles when the trout population will surge in both number and average size. He said the “Mo” is near the top of that cycle now, with high numbers of rainbow trout averaging 17-18 inches. Anglers willing to brave the cold are regularly rewarded.
 While rewards were angler-dependent on Sunday, brave souls were in abundant supply. Dozens of anglers stalked trout on both sides of the river near Wolf Creek. Fly fishermen in drift boats plied runs and spin fishers tended lines in the deep hole beneath the concrete face of Holter Dam.

John Arnold of Headhunters Fly Shop in Craig said the Missouri River has really exploded in popularity as a winter fishery over the last five years.

“I think more people are fishing in the winter,” Arnold said Tuesday. “The locals from Great Falls and Helena always have. The difference now is the regional crowd — Bozeman, Kalispell, Spokane, Calgary.”

Arnold said the Missouri owes its productivity as a winter fishery to Holter Dam. While the area gets extremely cold temperatures, the water discharged from the dam remains fairly constant. Arnold said water temperatures can hit 34 degree and below, but the slow flows and deep holds provide shelter for trout.

Arnold said the Missouri River supports an abundant number of crustaceans, namely scuds and sowbugs, on which the trout feed heavily. A pink scud pattern drifted deep through a hole will often produce fish.

While trout numbers are abundant on the Missouri, finding the fish can be a challenge. The broad, slow flows below Holter Dam can flummox anglers accustom to freestone streams and pocket water fishing.

“I think the most important thing to understand is that there are not fish everywhere on the Missouri,” Arnold said. “That is a common misconception. Those fish are going to congregate. The Missouri is not very defined if you compare it to other tailwaters like the Beaverhead or the Bighorn. You don’t have those defined drops and hard seams. Knowing the river is important.”

Arnold said high water during the 2011 floods wiped the river bottom clean. Many of the buckets and holes where fish once held have been eliminated, and new areas of refuge have formed. Because the flows tend to be gentle and the fish strong, they have no problem seeking out new lies.

“Guys think they are casting in six feet of water and they are casting in six inches,” Arnold said. “My advice is to move fast. If you find a place where the fish are biting, stay and fish. If you get one or two fish, there are probably 100 stacked up.”

When it comes to fly patterns for the Missouri, think pink. Pink Lightning Bugs, Rainbow Czech Nymphs and Ray Charles Sowbugs will catch fish. Try olive and green streamers or Clouser-type streamers with plenty of flash when the fish aren’t taking nymphs.

Per usual, be sure to bundle up for winter conditions.

And watch out for those bighorn.

“I think the biggest appeal of the Missouri is it is so close and so good when other rivers are frozen up,” King said. “In the winter there are not as many people fishing. It is my favorite time to fish up there for sure.”

Ben Pierce can be reached at bpierce@dailychronicle.com and 582-2625.