Lakes / Colorado / Boulder County / Sixmile Reservoir
Sixmile Reservoir, Colorado
101 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Colorado
40.07 degrees N, 105.22 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 Sixmile Reservoir Stacks Up
- Larger than 67% of the 778 lakes counted in Colorado.
- About 4 miles from Boulder, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Boulder Reservoir | Boulder | 0.8 mi | 536 acres |
| Hayden Lake | Boulder | 2.2 mi | 38 acres |
| Dodd Reservoir | Boulder | 3.0 mi | 28 acres |
| Left Hand Valley Reservoir | Boulder | 3.1 mi | 110 acres |
| Leggett and Hillcrest Reservoir | Boulder | 3.4 mi | 507 acres |
| Teller Lake Number 5 | Boulder | 4.9 mi | 31 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Sixmile Reservoir
How Big Is Sixmile Reservoir?
Sixmile Reservoir covers 101 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 128058397). Verified October 30, 2026.