Fly Fishing Missouri River - Below Holter Dam

The Missouri River below Holter Dam is one of Montana's premier tailwater fisheries, offering world-class fly fishing for large, healthy trout in a stunning high-plains setting. This massive tailwater is renowned for its incredible insect biomass, consistent flows, and trophy-sized trout that draw anglers from around the globe. The section flows through open ranchland and agricultural areas, with the Big Belt and Little Belt mountain ranges providing a spectacular backdrop. The combination of excellent water quality, stable flows, and exceptional trout populations makes this one of the most productive tailwater fisheries in the American West.

The tailwater section below Holter Dam is characterized by large, powerful flows that create diverse water types including fast riffles, deep runs, extensive gravel bars, and classic tailwater pools. The river bottom consists of cobble, gravel, and some sand, providing excellent habitat for both trout and aquatic insects. The gradient is moderate to gentle, creating excellent holding water throughout the section. The banks are lined with cottonwoods, willows, and agricultural fields, providing essential cover and shade. The water clarity is typically excellent, with stable temperatures year-round due to the tailwater releases from Holter Reservoir. This is big water that demands respect, with flows typically ranging from 3000 to 5000 CFS year-round.

This section supports exceptional populations of wild brown trout and rainbow trout, with fish typically ranging from 16 to 20 inches. The brown trout are particularly large and healthy, often exceeding 20 inches and occasionally reaching 26+ inches. Rainbow trout are also well-represented and known for their acrobatic fights and vibrant colors. The tailwater's stable flows and excellent food base support some of the highest trout densities in Montana, with over 4,000 fish per mile in some areas and reports of over 6,000 fish per mile in prime sections. Trophy fish exceeding 24 inches are common, with fish over 26 inches possible. Mountain whitefish are also abundant and provide consistent action.

Hatch activity is exceptional throughout the year, with a variety of mayflies, caddis, midges, and scuds providing consistent fishing opportunities. The tailwater is famous for its prolific midge hatches year-round, with small patterns (#18-22) being particularly effective. Pale Morning Duns (PMDs) and various caddis species provide excellent dry fly opportunities during late spring and early summer. Blue-winged Olives emerge in spring and fall, providing additional dry fly opportunities. Scuds and sowbugs are extremely abundant and provide consistent subsurface action. Streamer fishing can be particularly productive, especially when targeting larger brown trout. Nymphing with tandem rigs is highly productive year-round, as trout continue feeding on nymphs even when not visibly rising.

Optimal wading flows for the tailwater section range from 3000 to 5000 CFS, with flows above 6000 CFS reducing wading access but remaining excellent for float fishing. At 6000 CFS, wading anglers can still access most public sites but have reduced area to fish. For float fishing, 6000-8000 CFS represents ideal conditions. The river is excellent for float fishing in drift boats and rafts, with numerous access points making it easy to plan multi-day floats or shorter day trips. Access is excellent along I-15 and local roads, with numerous public access points, fishing access sites, and pullouts throughout the section. The towns of Craig, Cascade, and Great Falls provide excellent services, including fly shops, guides, and accommodations. The nearest major commercial airport is Great Falls International (GTF), approximately 60-90 minutes away depending on the section.

The Missouri River below Holter Dam is a world-class tailwater fishery that offers some of the finest fly fishing in Montana. Its combination of exceptional trout populations, stable flows, and year-round fishing opportunities makes it a bucket-list destination for serious fly anglers. The section's reputation for trophy-sized trout and incredible insect biomass makes it one of the most productive and sought-after tailwater fisheries in the American West.