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524-acre reservoir in Big Horn County, Montana. The lake tops out around 46 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. Here is how the season plays out for each species, straight from the data behind the map.
On the chart, Yellowtail Afterbay Reservoir draws 524 acres inside 4.4 miles of shoreline. At index 1.4 the outline is almost a bowl — read the depth changes, not the shoreline. About 35% of the surface sits shallower than 15 ft — that's the weed-and-bait zone. End to end it runs roughly 1.9 mi, about 0.6 mi across. The water lies in Big Horn County. Closest neighbour on DepthScout: Bighorn River, 14 mi northeast of here.
Spring puts rainbow trout in skinny water — 5 to 20 ft is the zone. Warm water sends them out to 8 to 30 ft; cold water stacks them in 8 to 40 ft. Break off the point is the standout, a drop-off at roughly 19 ft, rated prime for winter rainbow trout. Plan around early morning and the evening in the warm months. A dodger + spoon (deep troll) or a flutter spoon covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 20 ft | dawn & dusk | Main-lake point (12 ft) | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Break off the point (19 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Main-lake point (12 ft) | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 40 ft | dawn | Break off the point (19 ft) | Jigging spoon, Tube jig (white) |
Come spring, look for walleye tight to the bank in 4 to 15 ft. They move out to 15 to 35 ft in summer and finish the year down in 20 to 40 ft. If you only fish one area, make it Break off the point: a drop-off around 19 ft that scores prime in fall. Best bite is the evening and early morning. A crawler harness on bottom bouncer or a deep crankbait (trolled) is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | Main-lake point (12 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 15 to 35 ft | dusk & dawn | Break off the point (19 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 12 to 40 ft | dusk & night | Break off the point (19 ft) | Jigging rap, Jig + big minnow |
| Winter | 20 to 40 ft | dusk & dawn | Deep basin (31 ft) | Jigging spoon + minnow head, Rattle bait |
The spring pattern is a shallow one: channel catfish in 3 to 12 ft. As the season builds they drop to 8 to 25 ft, wintering in 20 to 40 ft. Top water on the chart: Deep basin, a deep basin in the 31 ft range, prime in winter. Time it for after dark and the evening.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Shallow bay flat (4 ft) | |
| Summer | 8 to 25 ft | night & dusk | Break off the point (19 ft) | |
| Fall | 10 to 30 ft | dusk | Deep basin (31 ft) | |
| Winter | 20 to 40 ft | midday | Deep basin (31 ft) |
Spring puts burbot in skinny water — 14 to 46 ft is the zone. Summer fish stay in 14 to 46 ft, and winter fish hold in 12 to 46 ft. Spring burbot concentrate at Deep basin, a prime-rated deep basin around 31 ft. Warm-month bites cluster around after dark and midday. A heavy jig + cut bait covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 14 to 46 ft | night & dusk | Deep basin (31 ft) | Glow jigging spoon + cut bait, Rattle bait (dark) |
| Summer | 14 to 46 ft | night & midday | Deep basin (31 ft) | Heavy jig + cut bait |
| Fall | 14 to 46 ft | night & dusk | Deep basin (31 ft) | Glow spoon + minnow head, Blade bait (slow) |
| Winter | 12 to 46 ft | night & dusk | Deep basin (31 ft) | Glow tungsten + cut bait, Rattle spoon + minnow head |
Spring puts common carp in skinny water — 2 to 10 ft is the zone. Warm water sends them out to 3 to 15 ft; cold water stacks them in 10 to 30 ft. Shallow bay flat is the standout, a weed flat at roughly 4 ft, rated prime for spring common carp. Plan around early morning and the evening in the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | midday & dawn | Shallow bay flat (4 ft) | |
| Summer | 3 to 15 ft | dawn & dusk | Shallow bay flat (4 ft) | |
| Fall | 5 to 18 ft | midday | Back-bay flat (7 ft) | |
| Winter | 10 to 30 ft | midday | Deep basin (31 ft) |
Come spring, look for yellow perch tight to the bank in 3 to 12 ft. Expect a summer slide to 10 to 30 ft, then a winter hold in 15 to 35 ft. Start at Shallow bay flat. It's a weed flat holding about 4 ft of water and rates prime come spring. Prime time lands in early morning. A drop-shot micro plastics or a small spoon tipped with worm is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (4 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Break off the point (19 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Deep basin (31 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Deep basin (31 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Yellowtail Afterbay Reservoir also holds brown trout (14 to 46 ft in summer), sauger (10 to 30 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Structure-wise the chart holds 6 features, led in depth by Deep basin at roughly 31 ft.
Access data: OpenStreetMap contributors (ODbL) — community-mapped launches. Confirm conditions and fees locally before you launch.
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 Yellowtail Afterbay Reservoir specifically, so confirm the current rules before you fish.
Check the official Montana fishing regulations →
Yellowtail Afterbay Reservoir is about 46 ft (14 m) deep at its deepest point. The depth chart here comes from real state fisheries GPS surveys, so the contours reflect measured depths.
Anglers target rainbow trout, walleye, channel catfish, burbot, common carp, yellow perch, brown trout, sauger on Yellowtail Afterbay Reservoir.
Break off the point is the top-rated area: a drop-off in about 19 ft of water that rates prime for walleye in fall. Every other rated spot, per species and season, is on the map above.
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.
Fishing on Yellowtail Afterbay 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.
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See how Yellowtail Afterbay Reservoir stacks up: best walleye lakes in Montana · best sauger lakes in Montana · best channel catfish lakes in Montana · best rainbow trout lakes in Montana
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.