Lakes / South Dakota / Sully County / Warnes Slough
Warnes Slough, South Dakota
364.97 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - South Dakota
44.61 degrees N, 100.24 degrees W - Sully 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 Warnes Slough Stacks Up
- Larger than 78% of the 533 lakes counted in South Dakota.
- About 18 miles from Pierre, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Sully Lake | Sully | 8.0 mi | 212.26 acres |
| Lake Okobojo | Sully | 9.4 mi | 91.68 acres |
| Lake Arikara | Hughes | 15 mi | 34.84 acres |
| Fuller Lake | Sully | 16 mi | 27.68 acres |
| Post Lake | Sully | 16 mi | 35.35 acres |
| Lake Oahe | Dewey | 21 mi | 309,912.57 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Warnes Slough
How Big Is Warnes Slough?
Warnes Slough covers 364.97 acres in Sully County, South Dakota.
What Is the Largest Lake in Sully County?
Stone Lake is the largest lake in Sully County, at 1,023.51 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 139477932). Verified October 30, 2026.