Lakes / Colorado / Larimer County / Flatiron Reservoir
Flatiron Reservoir, Colorado
41 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Colorado
40.37 degrees N, 105.23 degrees W - Larimer 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 Flatiron Reservoir Stacks Up
- Larger than 33% of the 778 lakes counted in Colorado.
- About 25 miles from Boulder, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Carter Lake Reservoir | Larimer | 2.6 mi | 1,120 acres |
| Pinewood Lake | Larimer | 2.8 mi | 91 acres |
| Lon Hagler Reservoir | Larimer | 4.3 mi | 150 acres |
| George Rist Reservoir | Larimer | 4.8 mi | 42 acres |
| Mariano Reservoir | Larimer | 4.8 mi | 376 acres |
| Hertha Reservoir | Larimer | 5.0 mi | 108 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Flatiron Reservoir
How Big Is Flatiron Reservoir?
Flatiron Reservoir covers 41 acres in Larimer County, Colorado.
What Is the Largest Lake in Larimer County?
Horsetooth Reservoir is the largest lake in Larimer County, at 1,817 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 120819373). Verified October 30, 2026.