The foothills of the middle Oldman, once home to bison--and mammoths before them--today feed whitetail and mule deer, black and grizzly bear, elk, and cattle. As the river passes through this wild natural area known as the Whaleback, cutthroats share green pools with rainbows introduced in the 1920s and 1930s. The mixed heritage is evident: some pure cutts, some pure rainbows, and plenty of hybrids.

The river gains natural nutrients through the Whaleback and holds more large fish. Above The Gap, a 17-inch cutt is a bragger, but through this stretch it takes around 20 inches to warrant a late-night phone call to a fishing buddy who couldn’t be there.

But if you want to catch the biggest possible fish in the Oldman, focus on the bull trout that chomp 12-inch cutthroats like bite-sized hors d’oeuvres. Unlike most of Montana, where it’s illegal to catch bull trout intentionally, in Alberta you can actively fish for bulls, as long as you handle them carefully and release them. There are good numbers of bull trout throughout the upper and middle Oldman. Target them by dancing big streamers through deep water and plunge pools on the end of a fast-sinking-tip line. If you do this with a true bull trout streamer, 5 or 6 inches long, you’ll catch bulls or nothing. But if you use a streamer about 3 inches long you’ll catch some bulls along with a larger class of cutts and rainbows.

The other bull trout technique is more reactive than proactive. You hook a small fish and while you’re bringing it in a big bull swoops out from under a rock and tries to take him away. This is startling, but after quickly releasing the little trout and calming down, you should cut back your leader, put on a big streamer, and make it behave like a cutthroat in trouble. And no, it’s not ethical to troll the little guy around the pool before you land him.

You probably won’t catch a 10-pound bull in the Oldman, but you may catch a 3- or 4- or 5-pounder--if you can tear yourself away from the dry-fly fishing.

The river flowing through The Gap is accessible from Highway 517. After leaving the Forest Reserve, the Oldman flows through private ranches where landowner permission is required. Farther downstream there is public access and a campground at the Waldron Bridge on paved Highway 22. Another bridge provides access on a gravel road 10 miles downstream.

The best dry-fly fishing in this middle section usually arrives alongside the Western Green Drake and lesser Green Drake (Flavilinea) hatches, which begin in early July and continue for five or six weeks. Blanket hatches rarely occur, but cloudy, calm, warm afternoons produce plenty of flies and rising fish. And on those days when all components are not in place, the fish often take a dry Green Drake anyway.

In the summer, carry dry Green Drake patterns (#10-12) like the Green Paradrake or Green Drake Thorax. If you want to fish a dry with a nymph, try a #10 yellow Rubber-legged Stimulator with a #16 Copper John. Bull trout hunters use streamers--#2 or larger--tied in colors to match cutthroat fry. It’s hard to beat a Clouser Minnow in pale pink or orange.

Conventional nymph-and-indicator fishing in this section is difficult because the water is deeper than it looks, and because there are frequent and sudden changes in depth--from knee deep to 15 feet deep just a few steps away. Most Oldman veterans concentrate on the heads of pools and shallower water, fishing drys solo or with small nymphs hanging a couple of feet beneath.

The middle river is wadeable but use caution. Though the bottom is not particularly slippery, it’s easy to be fooled by the exceptional water clarity and find yourself in deeper than you expect. Also, in some areas peculiar longitudinal or diagonal rock ledges protrude from the river bottom, and the deep slots between them make wading tricky.

Fifteen miles downstream of the Waldron Bridge, near the south end of the Porcupine Hills, the river enters the Oldman Reservoir, an irrigation storage reservoir created in the early 1990s by the Alberta government amid much opposition and controversy. Just north of the ranching town of Pincher Creek, the river emerges from beneath the Oldman Dam as one of Alberta’s few tailwater trout streams.

This article originally appeared in the July 2007 issue of Fly Fisherman.