Ostle Reservoir Depth Map & Fishing Spots (MT)

Hatch outlook

Grasshoppers (east-side summer)Active window

Typical here: Jul 1 – Oct 15 · until the hard frosts of mid-October; on the Missouri, August hoppers fish mid-river, not the banks

adultall day in high summer, best when afternoon wind knocks bugs onto the water

Pulls fish to the windward grassy banks and edges for months — fish the bank the wind blows ONTO.

The friendliest crossover of the summer: on lakes, drift the windward bank with a bubble-and-foam-hopper — the bubble's splash doesn't hurt a hopper presentation. On rivers, the same rig dead-drifted along the undercut grass banks, or small gold spinners under the banks between rises.

The event happens over grassy banks, undercut edges and windward shorelines

Spruce MothActive window

Typical here: Jul 20 – Aug 31 · a conifer-forest event — it needs fir and lodgepole on the banks, so it's a Rock Creek / Blackfoot / upper Bitterroot specialty

adultmorning through midday — moths don't enter the water willingly — landings are sporadic and near the conifer banks; fish the imitation LOW in the film with minimal floatant, even fully drowned, with a little movement

When the moths show, just about every run produces — large trout key on them so hard that one pattern carries the whole box for two weeks.

Honest limit: a small drowned-surface moth has no lure analog. The workable rig is a casting bubble with a drowned moth pattern along the timbered banks in the morning; otherwise fish spinners early and late and leave the moth window to the film.

2–3 weeks at best, and day-to-day — fish key on the moths when they show and vanish with them

The event happens over banks under conifers — the moths rarely reach mid-river

Recommendations come from depth structure and seasonal species behavior. Treat them as a starting point, not a guarantee. Contours here are interpolated from real agency depth surveys (state DNR / USACE). Never use for navigation. Always check local regulations.

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Recent catches at Ostle Reservoir

Shared by DepthScout anglers. Exact spots stay private, always.

No shared catches here yet — be the first.Log a catch from the map above and share it to put Ostle Reservoir on the board.

Fishing Ostle Reservoir: what the data says

27-acre reservoir in Teton County, Montana. The lake tops out around 4 ft. The depth chart is built from real state fisheries GPS surveys, so the humps, channels and drop-offs you see are measured, not guessed. What the data behind the map says about each species, season by season:

On the chart, Ostle Reservoir draws 27 acres inside 0.8 miles of shoreline. The basin is a simple one (shoreline index 1.1) — close to a bowl, so the structure on the chart matters more than the bank. There is no deep basin to speak of — the entire surface is under ~15 ft, prime weed water end to end. Tip to tip the water measures near 0.3 mi with a 0.2-mi widest point. You'll find it in Teton County. The nearest mapped water is Pishkun Reservoir, 21 mi to the south.

Rainbow Trout fishing at Ostle Reservoir

The spring pattern is a shallow one: rainbow trout in 1 to 4 ft. The depth story barely changes: 1 to 4 ft through summer, 1 to 4 ft in winter. Top water on the chart: Break off the point, a drop-off in the 4 ft range, prime in winter. Time it for early morning and the evening. Summer baits: a dodger + spoon (deep troll) or a flutter spoon gets it done.

Season	Depth	Best window	Start at	Go-to baits
Spring	1 to 4 ft	dawn & dusk	Main-lake point (2 ft)	Inline spinner (silver), Small spoon
Summer	1 to 4 ft	dawn & dusk	Break off the point (4 ft)	Dodger + spoon (deep troll), Flutter spoon
Fall	1 to 4 ft	dawn & dusk	Main-lake point (2 ft)	Casting spoon, Jerkbait over shoals
Winter	1 to 4 ft	dawn	Break off the point (4 ft)	Jigging spoon, Tube jig (white)

Muskellunge fishing at Ostle Reservoir

The spring pattern is a shallow one: muskellunge in 1 to 4 ft. The depth story barely changes: 1 to 4 ft through summer, 1 to 4 ft in winter. The spot to know is Break off the point, a drop-off in about 4 ft of water that rates prime for muskellunge in fall. Plan around the evening and early morning in the warm months. Summer baits: a double-10 bucktail or a topwater (walk-the-dog / creeper) gets it done.

Season	Depth	Best window	Start at	Go-to baits
Spring	1 to 4 ft	dusk	Main-lake point (2 ft)	Smaller bucktail (#8 blades), 6" glide bait
Summer	1 to 4 ft	dusk & dawn	Main-lake point (2 ft)	Double-10 bucktail, Topwater (walk-the-dog / creeper)
Fall	1 to 4 ft	midday & dusk	Break off the point (4 ft)	Big rubber (Bull Dawg style), 10"+ glide bait
Winter	1 to 4 ft	midday	Deep basin (4 ft)	Large rubber, crawled slow

Notable structure

Ostle Reservoir carries 4 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 4 ft down.

Deep basin: deep basin, around 4 ft
Break off the point: drop-off, around 4 ft
Main-lake point: point, around 2 ft
Secondary point: point, around 2 ft

Ostle Reservoir fishing regulations

Season dates, license requirements, and size and bag limits for Montana waters are set by the Montana Fish, Wildlife & Parks — and special regulations can apply to Ostle Reservoir specifically, so confirm the current rules before you fish.

Check the official Montana fishing regulations →

Common questions

How deep is Ostle Reservoir?

Ostle Reservoir is about 4 ft (1 m) deep at its deepest point. The depth chart here comes from real state fisheries GPS surveys, so the contours reflect measured depths.

What fish are in Ostle Reservoir?

Anglers target rainbow trout, muskellunge on Ostle Reservoir.

Where is the best fishing spot on Ostle Reservoir?

Break off the point is the top-rated area: a drop-off in about 4 ft of water that rates prime for muskellunge in fall. Open the map above to see every rated spot for each species and season.

When is the best time to fish Ostle Reservoir?

For rainbow trout, the summer bite is best in early morning and the evening. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.

What are the fishing regulations for Ostle Reservoir?

Fishing on Ostle Reservoir is regulated by the Montana Fish, Wildlife & Parks. Check the official Montana regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.

Nearby waters

Pishkun Reservoir 21 mi · Split Rock Lake 22 mi · Tunnel Lake 22 mi · Gibson Reservoir 26 mi · Lake Frances 28 mi · Willow Creek Reservoir 30 mi · Spotted Bear Lake 40 mi · East Tranquil Basin Lake 43 mi · West Tranquil Basin Lake 44 mi · Bean Lake 47 mi · Palisade Lake 48 mi · Sunburst Lake 48 mi

See how Ostle Reservoir stacks up: best rainbow trout lakes in Montana · best muskellunge lakes in Montana

More water nearby: Teton County fishing maps (5 charts). Browse all Montana fishing maps or see every water on DepthScout. Bathymetry credit: state fisheries survey programs. How we build these maps. Fish here with a sonar unit that logs? Send us your depth data and we'll improve this chart, credited to you. For fishing guidance only, never navigation.