Fly Fishing Sun River - Simms

The Sun River near Simms offers excellent freestone fly fishing in one of Central Montana's most productive and accessible fisheries, flowing through open ranchland and agricultural areas before joining the Missouri River. This section is characterized by fast-moving pocketwater, deep pools, and classic freestone runs that create diverse fishing opportunities throughout the season. The combination of excellent water quality, abundant wild trout, and good access makes this a popular destination for both local and visiting anglers seeking a classic Montana fly fishing experience.

The Simms section flows through relatively flat terrain, creating a mix of fast riffles, deep runs, and classic freestone pools. The river bottom consists of cobble, gravel, and some sand, providing diverse habitat for trout and aquatic insects. The gradient is moderate, 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 good, though it can become slightly off-color during high flows or agricultural runoff. This is a medium-sized freestone stream that is ideal for both wade and float fishing.

This section supports healthy populations of wild brown trout, rainbow trout, and native westslope cutthroat trout, with fish typically ranging from 12 to 16 inches. The brown trout are particularly aggressive and opportunistic, often responding well to attractor patterns, streamers, and terrestrials. Rainbow trout add variety and are known for their acrobatic fights. Native westslope cutthroat trout are present in the North Fork section and are protected by special regulations (all may be cutthroat trout, only 1 over 12 inches). Trophy fish exceeding 18 inches are possible, with fish over 20 inches occasionally caught. Mountain whitefish are also abundant and provide consistent action.

Hatch activity is good throughout the season, beginning after spring runoff subsides, typically in late May or early June. The section benefits from excellent mayfly and caddis hatches during summer, with various patterns producing exciting dry fly action. Blue-winged Olives emerge in spring and fall, PMDs appear in mid-summer, and various caddis species provide excellent evening fishing. Terrestrial patterns become extremely effective from mid-summer through early fall, with hoppers, ants, and beetles producing excellent results when fished tight to the banks. Streamer fishing can be particularly productive, especially during higher flows or when targeting larger brown trout. Nymphing remains productive year-round, with various mayfly, caddis, and stonefly patterns being effective.

Optimal wading flows for the Simms section range from 200 to 800 CFS, with flows above 1500 CFS becoming challenging for safe wading. Typical flows vary dramatically by season, with spring runoff peaks and lower flows in fall/winter. Multiple gages provide good flow coverage for monitoring conditions. The river is excellent for both wade and float fishing, with numerous access points making it easy to plan day trips. Access is good along local roads, with numerous public access points, fishing access sites, and pullouts throughout the section. The town of Simms provides limited services, with additional services available in Great Falls. The nearest major commercial airport is Great Falls International (GTF), approximately 30-45 minutes away.

The Sun River near Simms offers excellent fly fishing opportunities in one of Central Montana's most accessible freestone fisheries. Its combination of healthy wild trout populations, diverse water types, and good access makes it an ideal destination for anglers seeking a classic Montana fly fishing experience. The section's reputation for consistent fishing and excellent hatches makes it a popular choice for both local and visiting anglers.