Flowing through the heart of the Lamar Valley, the Lamar River is a classic meadow stream. The most popular section to fish, this valley reach features a relatively low gradient with long riffles and runs. The river is set in wide open country, though it frequently flows against high, undercut banks. Bison, wolves, and bears are often sighted along the stream. Above the confluence with Soda Butte Creek, the Lamar veers away from the road and into the wilderness. This stretch is only accessible by trail, and hikes range in length from a few minutes to a few days. As one travels upstream fishing pressure drops off dramatically, though the size of the fish decreases as well.
*Please check park fishing regulations before fishing. At the time of this writing, it is MANDATORY to kill any Rainbow Trout caught in the Lamar River drainage*
The Lamar River drainage is one of the last remaining strongholds of the Yellowstone Cutthroat Trout. There are some Rainbows around as well, and they will hybridize with the native Cutthroats. In the meadow section, the fish are typically in the 13-16 inch range, with fish up to 18" being pretty common. There are chances for bigger fish as well, but these fish see a lot of flies and are not easy to catch. As you move upstream, the size of the fish gradually decreases, though there are always some surprises.
Tactics and Techniques
The Lamar is primarily a dry fly fishery, although nymphs are sometimes necessary to ply the deep holes when the fish are not interested in rising. A 9ft 5wt fly rod is ideal here. The fish tend to be a little fussy, especially later in the season, so keep tippets light, 4X-6X, depending on time of year and size of fly. It is also sometimes helpful to lengthen your leader a few feet to help your presentation. While blind fishing can be productive on the Lamar, it is much easier when a hatch is going off and you can pinpoint the location of individual fish. I find that Cutthroats like to move around, so they are not always going to be in the same spots day in day out. Another important behavioral aspect of the fish here is that they rise to the fly extremely slowly, sometimes suspending just inches from the fly to inspect it more closely. It is imperative that you keep your cool and do not set the hook early in anticipation that the fish is going to eat your fly.
Fishing by Time of Year
The Lamar is always the last stream in Yellowtone Park to clear from spring runoff. The date is different every year based on the snowpack and weather, but I don't really count on the Lamar to be fishable before the middle of July most years. The river usually fishes well when it first clears because the fish have not seen any flies since the previous season. The most important thing to look for in July is the hatch of Pale Morning Duns, which typically come off from mid-morning until sometime after lunch. Green Drakes are possible this time of year as well, and this will really get the fish fired up. The Drakes, however, tend to be more of a scattered and fragmented hatch.
Later on in July and into August, the mayfly hatches begin to wane and terrestrial fishing begins to heat up. Hoppers are the main attraction, but don't ignore smaller terrestrials like beetles and ants. By this time in the season the fish have seen plenty of flies, so it's time to start downsizing your tippet and experimenting with fly patterns. August is also a great time to get into the backcountry and find some fish who haven't been so thoroughly educated. Backcountry fish on the Lamar will fall for the same menu of bugs that work in the meadow, but attractor patterns like PMX's and Turk's Tarantula's are important as well.
Terrestrial fishing continues to produce in September, but the fish are spooky. As the weather begins to cool a bit Mayfly hatches start to pick back up. Be prepared for Blue Winged Olives, Fall Drakes, and Midges. Cloudy days are best for hatches but you will often encounter scattered hatches on sunny days as well. This pattern continues until the cold weather sets in sometime late in September or October. The Lamar does not fish well in the cold. You could always dry to dredge one up on an indicator rig, but the time to fish the Lamar is when there are bugs hatching as fish feeding on the surface.
Contact Montana Angler Fly Fishing for guided fly fishing trips in Yellowstone National Park