Lakes / Idaho / Adams County / Lost Valley Reservoir
Lost Valley Reservoir, Idaho
726 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Idaho
44.97 degrees N, 116.46 degrees W - Adams 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 Lost Valley Reservoir Stacks Up
- Larger than 85% of the 316 lakes counted in Idaho.
- The largest lake in Adams County among those counted.
- About 94 miles from Boise, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Black Lake | Adams | 16 mi | 25.7 acres |
| Goose Lake | Adams | 16 mi | 378.07 acres |
| Hait Reservoir | Valley | 16 mi | 67.97 acres |
| Twin Lakes | Adams | 17 mi | 39.78 acres |
| Hornet Reservoir | Washington | 18 mi | 31.52 acres |
| Brundage Reservoir | Adams | 18 mi | 281.7 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Lost Valley Reservoir
How Big Is Lost Valley Reservoir?
Lost Valley Reservoir covers 726 acres in Adams County, Idaho.
What Is the Largest Lake in Adams County?
Lost Valley Reservoir is the largest lake in Adams County, at 726 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 38103670). Verified October 30, 2026.