Gollaher 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 Gollaher 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 Gollaher Reservoir on the board.

Fishing Gollaher Reservoir: what the data says

40-acre reservoir in Cascade County, Montana. The lake tops out around 18 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. Below is the species-by-species picture, pulled from the same data the map uses.

Gollaher Reservoir maps at 40 acres behind 1.2 miles of shoreline. Its 1.3 shoreline index means few bank features; the contours below do the pattern work. 94% of the surface is littoral (under ~15 ft) — cover, weeds and forage water. End to end it runs roughly 0.5 mi, about 0.2 mi across. It sits in Cascade County. Missouri River sits 10 mi west — the closest neighbouring chart.

Brook Trout fishing at Gollaher Reservoir

When the water first warms, brook trout slide up into 2 to 15 ft. By summer they slide out to 5 to 18 ft, and by winter most fish are in 3 to 18 ft. If you only fish one area, make it Deep basin: a deep basin around 18 ft that scores prime in summer. In summer the feeding windows fall in early morning and the evening. Keep a small spoon fished deep or a trolled lake-clear wobbler + worm rigged through the warm months.

Season	Depth	Best window	Start at	Go-to baits
Spring	2 to 15 ft	dawn & dusk	Main-lake point (3 ft)	Small inline spinner (gold), Tiny spoon
Summer	5 to 18 ft	dawn & dusk	Deep basin (18 ft)	Small spoon fished deep, Trolled lake-clear wobbler + worm
Fall	2 to 15 ft	midday & dawn	Main-lake point (3 ft)	Small spoon (orange), Spinner
Winter	3 to 18 ft	dawn	Deep basin (18 ft)	Small jigging spoon, Tungsten jig + plastic

Rainbow Trout fishing at Gollaher Reservoir

Come spring, look for rainbow trout tight to the bank in 5 to 18 ft. Through summer count on 5 to 18 ft; the winter hold is 4 to 18 ft. Start at Break off the point. It's a drop-off holding about 5 ft of water and rates prime come winter. Prime time lands in early morning and the evening. A dodger + spoon (deep troll) or a flutter spoon is the honest summer answer here.

Season	Depth	Best window	Start at	Go-to baits
Spring	5 to 18 ft	dawn & dusk	Break off the point (5 ft)	Inline spinner (silver), Small spoon
Summer	5 to 18 ft	dawn & dusk	Break off the point (5 ft)	Dodger + spoon (deep troll), Flutter spoon
Fall	5 to 18 ft	dawn & dusk	Break off the point (5 ft)	Casting spoon, Jerkbait over shoals
Winter	4 to 18 ft	dawn	Break off the point (5 ft)	Jigging spoon, Tube jig (white)

Cutthroat Trout fishing at Gollaher Reservoir

Start shallow in spring: cutthroat trout sit in 3 to 15 ft that time of year. Warm water sends them out to 5 to 18 ft; cold water stacks them in 5 to 18 ft. Top water on the chart: Break off the point, a drop-off in the 5 ft range, prime in summer. Fish it in early morning and the evening and you'll meet the bite. Throw a trolled spoon (small) or an inline spinner until the fish tell you otherwise.

Season	Depth	Best window	Start at	Go-to baits
Spring	3 to 15 ft	dawn & dusk	Main-lake point (3 ft)	Inline spinner (silver/gold), Small spoon
Summer	5 to 18 ft	dawn & dusk	Break off the point (5 ft)	Trolled spoon (small), Inline spinner
Fall	4 to 18 ft	dawn & dusk	Main-lake point (3 ft)	Casting spoon, Inline spinner
Winter	5 to 18 ft	dawn	Break off the point (5 ft)	Small jigging spoon, Marabou jig

Yellow Perch fishing at Gollaher Reservoir

Spring puts yellow perch in skinny water — 3 to 12 ft is the zone. Warm water sends them out to 5 to 18 ft; cold water stacks them in 5 to 18 ft. Shallow bay flat is the standout, a weed flat at roughly 6 ft, rated prime for spring yellow perch. Plan around early morning in the warm months. A drop-shot micro plastics or a small spoon tipped with worm covers the summer program.

Season	Depth	Best window	Start at	Go-to baits
Spring	3 to 12 ft	midday & dawn	Shallow bay flat (6 ft)	Small jig + curly tail, Perch-pattern micro crank
Summer	5 to 18 ft	dawn	Deep basin (18 ft)	Drop-shot micro plastics, Small spoon tipped with worm
Fall	5 to 18 ft	midday	Deep basin (18 ft)	Jigging spoon (small), Perch rig / spreader
Winter	5 to 18 ft	midday & dawn	Deep basin (18 ft)	Tungsten jig + spikes, Rattle spoon (small)

Northern Pike fishing at Gollaher Reservoir

Spring northern pike on Gollaher Reservoir hold shallow, usually 2 to 8 ft. They move out to 5 to 18 ft in summer and finish the year down in 5 to 15 ft. Put Shallow bay flat first on the milk run — a weed flat near 6 ft that grades prime for spring. The feeding windows run early morning and the evening. The summer box starts with a bucktail or a weedless spoon over cabbage.

Season	Depth	Best window	Start at	Go-to baits
Spring	2 to 8 ft	midday & dawn	Shallow bay flat (6 ft)	#5 inline spinner, Spoon (red/white)
Summer	5 to 18 ft	dawn & dusk	Shallow bay flat (6 ft)	Bucktail, Weedless spoon over cabbage
Fall	6 to 18 ft	midday & dawn	Shallow bay flat (6 ft)	Big rubber (Bull Dawg style), Husky-style jerkbait
Winter	5 to 15 ft	midday	Shallow bay flat (6 ft)	Tip-ups, Large jigging spoon

Notable structure

Gollaher Reservoir carries 4 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 18 ft down.

Deep basin: deep basin, around 18 ft
Shallow bay flat: weed flat, around 6 ft
Break off the point: drop-off, around 5 ft
Main-lake point: point, around 3 ft

Gollaher 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 Gollaher Reservoir specifically, so confirm the current rules before you fish.

Check the official Montana fishing regulations →

Common questions

How deep is Gollaher Reservoir?

Gollaher Reservoir is about 18 ft (5 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 Gollaher Reservoir?

Anglers target brook trout, rainbow trout, cutthroat trout, yellow perch, northern pike on Gollaher Reservoir. This isn't a survey of the lake — none is on record for it — but an informed estimate from the species listed for the nearest surveyed lakes in the region, filtered to this lake's depth and habitat.

Where is the best fishing spot on Gollaher Reservoir?

Break off the point is the top-rated area: a drop-off in about 5 ft of water that rates prime for cutthroat trout in summer. Open the map above to see every rated spot for each species and season.

When is the best time to fish Gollaher Reservoir?

For brook 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 Gollaher Reservoir?

Fishing on Gollaher 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

Missouri River 10 mi · Hound Creek Reservoir 15 mi · Lewis Pond South 22 mi · Wadsworth Lake 23 mi · Hauser Lake 36 mi · Bean Lake 38 mi · Lake Helena 39 mi · Willow Creek Reservoir 45 mi · Spring Meadow Lake 47 mi · Heart Lake (Lewis and Clark) 49 mi · Canyon Ferry Reservoir 49 mi · Pishkun Reservoir 51 mi

See how Gollaher Reservoir stacks up: best northern pike lakes in Montana · best rainbow trout lakes in Montana · best yellow perch lakes in Montana · best brook trout lakes in Montana

More water nearby: Cascade 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.