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Fishing Gross Reservoir: what the data says
415-acre reservoir near Boulder County. The lake tops out around 299 ft. The contours are modeled from the water's real shoreline and maximum depth. Treat them as a rough guide, and never use them for navigation. Here is how the season plays out for each species, straight from the data behind the map.
Muskellunge fishing at Gross Reservoir
Spring muskellunge on Gross Reservoir hold shallow, usually 3 to 12 ft. By summer they slide out to 8 to 25 ft, and by winter most fish are in 15 to 35 ft. The spot to know is Shallow bay flat, a weed flat in about 6 ft of water that rates prime for muskellunge in spring. In summer the feeding windows fall in the evening and early morning. Summer baits: a double-10 bucktail or a topwater (walk-the-dog / creeper) gets it done.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Smaller bucktail (#8 blades), 6" glide bait |
| Summer | 8 to 25 ft | dusk & dawn | Double-10 bucktail, Topwater (walk-the-dog / creeper) |
| Fall | 8 to 30 ft | midday & dusk | Big rubber (Bull Dawg style), 10"+ glide bait |
| Winter | 15 to 35 ft | midday | Large rubber, crawled slow |
Kokanee fishing at Gross Reservoir
In spring, kokanee run shallow here, mostly 10 to 30 ft. They move out to 30 to 70 ft in summer and finish the year down in 20 to 80 ft. If you only fish one area, make it Deep basin: a deep basin around 254 ft that scores good in spring. Best bite is early morning. Summer baits: a dodger + pink/orange squid on downrigger or a kokanee bug + corn gets it done.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 10 to 30 ft | dawn | Small dodger + squid (pink), Wedding-ring spinner + corn |
| Summer | 30 to 70 ft | dawn | Dodger + pink/orange squid on downrigger, Kokanee bug + corn |
| Fall | 5 to 40 ft | dawn | Dodger + squid (deeper red/purple), Small spoon |
| Winter | 20 to 80 ft | dawn | Small glow jig + corn or maggot, Tiny spoon |
Brook Trout fishing at Gross Reservoir
Spring brook trout on Gross Reservoir hold shallow, usually 2 to 15 ft. They move out to 10 to 30 ft in summer and finish the year down in 3 to 20 ft. The spot to know is Shallow bay flat, a weed flat in about 6 ft of water that rates good for brook trout in spring. Plan around early morning and the evening in the warm months. Summer baits: a small spoon fished deep or a trolled lake-clear wobbler + worm gets it done.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Small jigging spoon, Tungsten jig + plastic |
Brown Trout fishing at Gross Reservoir
Start shallow in spring: brown trout sit in 3 to 25 ft that time of year. By summer they slide out to 25 to 60 ft, and by winter most fish are in 5 to 35 ft. If you only fish one area, make it Break off the point: a drop-off around 135 ft that scores good in summer. In summer the feeding windows fall in after dark and early morning. A spoon at the thermocline or a deep stickbait (night) covers the summer program.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 3 to 25 ft | dawn & dusk | Stickbait off planer boards (shallow), Small spoon along mud lines |
| Summer | 25 to 60 ft | night & dawn | Spoon at the thermocline, Deep stickbait (night) |
| Fall | 5 to 30 ft | dusk & dawn | Jerkbait over gravel, Casting spoon |
| Winter | 5 to 35 ft | dawn | Jigging spoon, Small stickbait (slow) |
Lake Trout fishing at Gross Reservoir
In spring, lake trout run shallow here, mostly 10 to 40 ft. By summer they slide out to 50 to 120 ft, and by winter most fish are in 20 to 80 ft. Break off the point is the standout, a drop-off at roughly 135 ft, rated good for summer lake trout. In summer the feeding windows fall in early morning. Summer baits: a white tube jig (deep) or a magnum spoon on downrigger gets it done.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 50 to 120 ft | dawn | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Heavy casting spoon, Jigging rap over reefs |
| Winter | 20 to 80 ft | dawn | White tube jig, Airplane jig |
Rainbow Trout fishing at Gross Reservoir
Start shallow in spring: rainbow trout sit in 5 to 20 ft that time of year. Summer pushes them deeper, 8 to 30 ft, and winter fish settle into 8 to 40 ft. The spot to know is Break off the point, a drop-off in about 135 ft of water that rates good for rainbow trout in winter. In summer the feeding windows fall in early morning and the evening. Tie on a dodger + spoon (deep troll) or a flutter spoon and you're in the game.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 5 to 20 ft | dawn & dusk | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 40 ft | dawn | Jigging spoon, Tube jig (white) |
Gross Reservoir also holds cutthroat trout (10 to 35 ft in summer), splake (25 to 60 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Notable structure
- Deep basin: deep basin, around 254 ft
- Break off the point: drop-off, around 135 ft
- Main-lake point: point, around 75 ft
- Secondary point: point, around 75 ft
- Shallow bay flat: weed flat, around 6 ft
- Back-bay flat: weed flat, around 6 ft
Common questions
How deep is Gross Reservoir?
Gross Reservoir is about 299 ft at its deepest point. The contours here are modeled from the water's real shape and maximum depth, so treat them as a rough guide.
What fish are in Gross Reservoir?
Anglers target rainbow trout, muskellunge, lake trout, brown trout, brook trout, kokanee, cutthroat trout, splake on Gross Reservoir.
Where is the best fishing spot on Gross Reservoir?
Shallow bay flat is the top-rated area: a weed flat in about 6 ft of water that rates prime for muskellunge in spring. Open the map above to see every rated spot for each species and season.
When is the best time to fish Gross Reservoir?
For muskellunge, the summer bite is best in the evening and early morning. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Nearby waters
Barker Reservoir · Boulder City Reservoir · Arvada Reservoir · Standley Lake · Waneka Lake · Button Rock Res
See how Gross Reservoir stacks up: best rainbow trout lakes in Colorado · best lake trout lakes in Colorado · best brown trout lakes in Colorado · best brook trout lakes in Colorado
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