Lakes / Illinois / Macon County / Lake Decatur
Lake Decatur, Illinois
2,904.48 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Illinois
39.85 degrees N, 88.90 degrees W - Macon 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 Lake Decatur Stacks Up
- Ranks #10 for surface area among the Illinois lakes counted so far - 2,904.48 acres.
- About 40 miles from Springfield, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Weldon Springs Lake | De Witt | 19 mi | 27.43 acres |
| Lake Clinton | De Witt | 22 mi | 4,585.53 acres |
| Lake Shelbyville | Shelby | 26 mi | 10,235.1 acres |
| Wood Lake | Moultrie | 27 mi | 33.61 acres |
| Bertinetti Lake | Christian | 28 mi | 49.12 acres |
| National Petroleum Chemical Company Plant Reservoir | Douglas | 29 mi | 25.22 acres |
Straight-line distance between lake centers.
Facts and Figures
Largest Lakes in Illinois
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | Carlyle Lake | Clinton | 22,796.77 acres | - |
| 2 | Mine Number 21 Reservoir | Franklin | 17,062.04 acres | - |
| 3 | Upper Peoria Lake | Woodford | 15,460.64 acres | - |
| 4 | Lake Shelbyville | Shelby | 10,235.1 acres | - |
| 5 | Crab Orchard Lake | Williamson | 7,292.57 acres | - |
All 511 Illinois lakes ranked by surface area
Sources: USGS National Hydrography Dataset (The National Map) lake data (ID 131194651). Verified October 30, 2026.