Lakes / Idaho / Elmore County / Long Tom Reservoir
Long Tom Reservoir, Idaho
100.89 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Idaho
43.29 degrees N, 115.58 degrees W - Elmore 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 Long Tom Reservoir Stacks Up
- Larger than 58% of the 316 lakes counted in Idaho.
- About 39 miles from Boise, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Little Camas Reservoir | Elmore | 10 mi | 1,048.34 acres |
| Anderson Ranch Reservoir | Elmore | 14 mi | 4,515.55 acres |
| Upper Teapot Reservoir | Elmore | 18 mi | 46.54 acres |
| Lower Teapot Reservoir | Elmore | 19 mi | 64.25 acres |
| Blair Trail Reservoir | Elmore | 21 mi | 177.67 acres |
| Morrow Reservoir | Elmore | 23 mi | 43 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Long Tom Reservoir
How Big Is Long Tom Reservoir?
Long Tom Reservoir covers 100.89 acres in Elmore County, Idaho.
What Is the Largest Lake in Elmore County?
Anderson Ranch Reservoir is the largest lake in Elmore County, at 4,515.55 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 53240072). Verified October 30, 2026.