Lakes / Idaho / Fremont County / Island Park Reservoir
Island Park Reservoir, Idaho
7,550.45 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Idaho
44.40 degrees N, 111.51 degrees W - Fremont 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 Island Park Reservoir Stacks Up
- Larger than 96% of the 316 lakes counted in Idaho.
- The largest lake in Fremont County among those counted.
- About 68 miles from Idaho Falls, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Golden Lake | Fremont | 3.5 mi | 42.5 acres |
| Silver Lake | Fremont | 5.3 mi | 163.34 acres |
| Fish Pond | Fremont | 7.8 mi | 28.17 acres |
| Swan Lake | Fremont | 8.2 mi | 30.89 acres |
| Sheridan Reservoir | Clark | 10 mi | 322.97 acres |
| Sand Creek Reservoir | Fremont | 15 mi | 79.58 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Island Park Reservoir
How Big Is Island Park Reservoir?
Island Park Reservoir covers 7,550.45 acres in Fremont County, Idaho.
What Is the Largest Lake in Fremont County?
Island Park Reservoir is the largest lake in Fremont County, at 7,550.45 acres.
Largest Lakes in Idaho
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | Lake Pend Oreille | Bonner | 92,764.44 acres | - |
| 2 | American Falls Reservoir | Power | 55,319.78 acres | - |
| 3 | Coeur d'Alene Lake | Kootenai | 26,891.64 acres | - |
| 4 | Lake Cascade | Valley | 25,043.4 acres | - |
| 5 | Priest Lake | Bonner | 23,425.59 acres | - |
All 316 Idaho lakes ranked by surface area
Sources: USGS National Hydrography Dataset (The National Map) lake data (ID 52168231). Verified October 30, 2026.