Lakes / Idaho / Caribou County / Alexander Reservoir
Alexander Reservoir, Idaho
1,007.26 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Idaho
42.65 degrees N, 111.65 degrees W - Caribou 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 Alexander Reservoir Stacks Up
- Larger than 88% of the 316 lakes counted in Idaho.
- About 61 miles from Idaho Falls, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Hole in the Rock | Caribou | 13 mi | 146.29 acres |
| Blackfoot Reservoir | Caribou | 18 mi | 16,913.5 acres |
| Twentyfour Mile Reservoir | Caribou | 21 mi | 37.31 acres |
| Chesterfield Reservoir | Caribou | 23 mi | 1,264.44 acres |
| Oneida Narrows Reservoir | Franklin | 25 mi | 429.96 acres |
| Swan Lake | Bannock | 30 mi | 60.29 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Alexander Reservoir
How Big Is Alexander Reservoir?
Alexander Reservoir covers 1,007.26 acres in Caribou County, Idaho.
What Is the Largest Lake in Caribou County?
Blackfoot Reservoir is the largest lake in Caribou County, at 16,913.5 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 120011754). Verified October 30, 2026.