Lakes / Colorado / Jefferson County / Ralston Reservoir
Ralston Reservoir, Colorado
154 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Colorado
39.83 degrees N, 105.25 degrees W - Jefferson 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 Ralston Reservoir Stacks Up
- Larger than 76% of the 778 lakes counted in Colorado.
- About 13 miles from Boulder, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Upper Long Lake | Jefferson | 0.7 mi | 53 acres |
| Blunn Reservoir | Jefferson | 2.0 mi | 163 acres |
| Tucker Lake | Jefferson | 2.6 mi | 67 acres |
| Rocky Flats Lake | Jefferson | 3.2 mi | 43 acres |
| Leyden Lake | Jefferson | 4.2 mi | 57 acres |
| Hyatt Lake | Jefferson | 4.7 mi | 70 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Ralston Reservoir
How Big Is Ralston Reservoir?
Ralston Reservoir covers 154 acres in Jefferson County, Colorado.
What Is the Largest Lake in Jefferson County?
Chatfield Lake is the largest lake in Jefferson County, at 1,389 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 116935969). Verified October 30, 2026.