Lakes / Colorado / Boulder County / Gross Reservoir
Gross Reservoir, Colorado
415 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Colorado
39.95 degrees N, 105.37 degrees W - Boulder County. State and county outlines drawn from Census boundary data; the lake marker is placed by its USGS National Hydrography Dataset coordinates, not by eye. Schematic - not a survey map.
How Gross Reservoir Stacks Up
- Larger than 88% of the 778 lakes counted in Colorado.
- About 7 miles from Boulder, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Barker Reservoir | Boulder | 6.7 mi | 198 acres |
| Marshall Lake | Boulder | 8.3 mi | 220 acres |
| Rocky Flats Lake | Jefferson | 8.9 mi | 43 acres |
| Base Line Reservoir | Boulder | 9.4 mi | 261 acres |
| Hayden Lake | Boulder | 9.4 mi | 38 acres |
| Gold Lake | Boulder | 10 mi | 31 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Gross Reservoir
How Big Is Gross Reservoir?
Gross Reservoir covers 415 acres in Boulder County, Colorado.
What Is the Largest Lake in Boulder County?
Boulder Reservoir is the largest lake in Boulder County, at 536 acres.
Largest Lakes in Colorado
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | John Martin Reservoir | Bent | 11,686 acres | - |
| 2 | Blue Mesa Reservoir | Gunnison | 8,944 acres | - |
| 3 | Lake Granby | Grand | 7,075 acres | - |
| 4 | Lake Meredith | Crowley | 5,539 acres | - |
| 5 | Adobe Creek Reservoir | Bent | 4,770 acres | - |
All 778 Colorado lakes ranked by surface area
Sources: USGS NHD (The National Map NHD MapServer layer 12) named waterbodies FTYPE 390/436; counties via Census point-in-polygon lake data (ID 128059052). Verified October 30, 2026.