Lakes / South Dakota / Marshall County / Flat Lake
Flat Lake, Marshall County, South Dakota
176.93 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - South Dakota
45.80 degrees N, 97.40 degrees W - Marshall 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 Flat Lake Stacks Up
- Larger than 60% of the 533 lakes counted in South Dakota.
- About 57 miles from Aberdeen, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Wise Spirit Lake | Marshall | 2.0 mi | 67.95 acres |
| Isabelle Lake | Marshall | 2.1 mi | 137.64 acres |
| Abraham Lake | Marshall | 2.2 mi | 122.32 acres |
| Hoop Lake | Marshall | 2.2 mi | 124.79 acres |
| Dumarce Lake | Marshall | 3.1 mi | 196.2 acres |
| Silver Lake | Marshall | 3.2 mi | 43.74 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Flat Lake
How Big Is Flat Lake?
Flat Lake covers 176.93 acres in Marshall County, South Dakota.
What Is the Largest Lake in Marshall County?
Buffalo Lakes is the largest lake in Marshall County, at 1,986.48 acres.
Largest Lakes in South Dakota
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | Lake Oahe | Dewey | 309,912.57 acres | - |
| 2 | Lake Francis Case | Charles Mix | 82,166.92 acres | - |
| 3 | Lake Sharpe | Hughes | 58,419.67 acres | - |
| 4 | Lewis and Clark Lake | Bon Homme | 25,141.99 acres | - |
| 5 | Lake Thompson | Kingsbury | 13,887.93 acres | - |
All 533 South Dakota lakes ranked by surface area
Sources: USGS National Hydrography Dataset (The National Map) lake data (ID 144884494). Verified October 30, 2026.