- Top state
- 69%
- Florida
- Top county
- >99%
- Lafourche Parish, LA
- Poorly drained, US
- 22%
- share of all mapped land
States with the most poorly drained soil
Share of mapped land
| State | Poorly drained | Water table near surface | Floods occasionally or often |
|---|---|---|---|
| 1. Florida | 69% | 62% | 15% |
| 2. Louisiana | 61% | 48% | 32% |
| 3. Illinois | 58% | 54% | 12% |
| 4. Minnesota | 55% | 52% | 4% |
| 5. Indiana | 46% | 54% | 9% |
| 6. Michigan | 45% | 49% | 2% |
| 7. Iowa | 45% | 43% | 12% |
| 8. Alaska | 44% | 44% | 10% |
| 9. Ohio | 41% | 49% | 6% |
| 10. Maine | 41% | 47% | 2% |
| 11. Delaware | 36% | 38% | 11% |
| 12. Mississippi | 35% | 32% | 27% |
| 13. Arkansas | 33% | 30% | 13% |
| 14. South Carolina | 33% | 35% | 13% |
| 15. Wisconsin | 33% | 37% | 6% |
The 25 wettest counties
Share of mapped land
| County | Poorly drained | Water table near surface | Most common soil |
|---|---|---|---|
| 1. Lafourche Parish, LA | >99% | 83% | Allemands |
| 2. Jefferson Parish, LA | >99% | 74% | LaFitte |
| 3. Clinch County, GA | >99% | 96% | Surrency |
| 4. Assumption Parish, LA | >99% | 73% | Barbary |
| 5. Plaquemines Parish, LA | >99% | 81% | Clovelly |
| 6. Hendry County, FL | >99% | 99% | Oldsmar |
| 7. St. Bernard Parish, LA | >99% | 87% | Scatlake |
| 8. Sharkey County, MS | >99% | 81% | Sharkey |
| 9. Vermilion Parish, LA | >99% | 68% | Allemands |
| 10. Glades County, FL | 99% | 96% | Immokalee |
| 11. Iberville Parish, LA | 99% | 66% | Sharkey |
| 12. DeSoto County, FL | 99% | 95% | Smyrna |
| 13. Baker County, FL | 98% | 90% | Pamlico |
| 14. Tyrrell County, NC | 98% | 98% | Pungo |
| 15. Okeechobee County, FL | 98% | 95% | Myakka |
| 16. St. John the Baptist Parish, LA | 98% | 83% | Barbary |
| 17. Charlton County, GA | 98% | 90% | Dasher |
| 18. St. Charles Parish, LA | 98% | 77% | Kenner |
| 19. Iberia Parish, LA | 97% | 69% | Fausse |
| 20. Ascension Parish, LA | 97% | 62% | Schriever |
| 21. Camden County, GA | 97% | 78% | Bohicket |
| 22. St. James Parish, LA | 97% | 75% | Barbary |
| 23. Hardee County, FL | 97% | 88% | Pomona |
| 24. Glynn County, GA | 97% | 80% | Bohicket |
| 25. Audrain County, MO | 96% | 87% | Mexico |
Why the Corn Belt is on this list
Illinois, Indiana, Iowa and Ohio are some of the most productive farmland in the world, and much of it was wet prairie and swamp before farmers laid buried drain tile. The soil survey describes the soil as it is naturally, before drainage, so a field or subdivision with tile can be drier than its rating suggests.
For homeowners, poorly drained soil means a seasonal high water table: soggy lawns in spring, sump pumps that run, and basements that need good waterproofing. Rain gardens and native wet-meadow plants turn the problem into a feature.
Sources & data dates
- Source
- USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
- Data date
- SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
- Scope
- All mapped land in the 50 states and DC in the current soil survey.
- Method
- County rankings include counties with at least 100,000 acres of mapped land and soil ratings on at least 80% of it, so a small county with one unusual map unit cannot top the list. Counties without a full report on this site are named but not linked; the ZIP lookup covers them. Poorly drained combines the NRCS natural drainage classes somewhat poorly, poorly and very poorly drained. Water table near surface means a saturated layer within 18 inches of the surface in at least one month. Full methodology.