Lakes / Missouri / St. Charles County / Alton Slough
Alton Slough, Missouri
386.08 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Missouri
38.87 degrees N, 90.17 degrees W - St. Charles 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 Alton Slough Stacks Up
- Larger than 90% of the 352 lakes counted in Missouri.
- About 17 miles from St. Louis, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Spatterdock Lake | St. Charles | 4.2 mi | 75.37 acres |
| Spanish Lake | St. Louis | 5.3 mi | 30.89 acres |
| Creve Coeur Lake | St. Louis | 20 mi | 303.2 acres |
| Horseshoe Lake | St. Charles | 29 mi | 51.65 acres |
| Grassy Lake | St. Charles | 29 mi | 51.15 acres |
| Mud Lake | St. Charles | 29 mi | 77.1 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Alton Slough
How Big Is Alton Slough?
Alton Slough covers 386.08 acres in St. Charles County, Missouri.
What Is the Largest Lake in St. Charles County?
Lake Saint Louis is the largest lake in St. Charles County, at 444.3 acres.
Largest Lakes in Missouri
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | Lake of the Ozarks | Camden | 51,171.75 acres | - |
| 2 | Harry S Truman Reservoir | Benton | 49,365.93 acres | - |
| 3 | Table Rock Lake | Stone | 41,777.86 acres | - |
| 4 | Stockton Lake | Cedar | 24,962.34 acres | - |
| 5 | Mark Twain Lake | Ralls | 18,362.33 acres | - |
All 352 Missouri lakes ranked by surface area
Sources: USGS National Hydrography Dataset (The National Map) lake data (ID 120032458). Verified October 30, 2026.