Lakes / Illinois / Grundy County / Heidecke Lake
Heidecke Lake, Illinois
1,913.34 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Illinois
41.37 degrees N, 88.34 degrees W - Grundy 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 Heidecke Lake Stacks Up
- Larger than 96% of the 511 lakes counted in Illinois.
- The largest lake in Grundy County among those counted.
- About 51 miles from Chicago, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Negro Slough | Grundy | 1.1 mi | 26.69 acres |
| Goose Lake | Grundy | 3.1 mi | 40.53 acres |
| Dresden Cooling Lake | Will | 5.1 mi | 1,105.8 acres |
| Milliken Lake | Will | 8.5 mi | 25.95 acres |
| Hawk Lake | Will | 9.5 mi | 31.41 acres |
| Braidwood Power Plant Cooling Pond | Will | 12 mi | 2,539.39 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Heidecke Lake
How Big Is Heidecke Lake?
Heidecke Lake covers 1,913.34 acres in Grundy County, Illinois.
What Is the Largest Lake in Grundy County?
Heidecke Lake is the largest lake in Grundy County, at 1,913.34 acres.
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 90567371). Verified October 30, 2026.