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USSoilMap

Soil Drainage Map

Search an address to see the soil’s natural drainage class there, from excessively drained to very poorly drained. Below the map: how US acres split across the classes, and which states run wettest.

US addresses only: street address, city and state, or ZIP.

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The map shows USDA’s typical values for each map unit[1]; test your own soil before acting on them. See improving soil drainage and water table depth.

USDA gives the soils it maps a natural drainage class, from excessively drained to very poorly drained. It says how fast water leaves and how long the soil stays wet[2]. 57% of US soil acres with a drainage class are well drained, and 17% are poorly or very poorly drained, led by Florida (66%)[2][1].

Reading the map

Each polygon is colored by the USDA natural drainage class of its dominant soil, from excessively drained (sandy tan) to very poorly drained (dark blue)[2].

  • Excessively drained: water is removed very rapidly.
  • Somewhat excessively drained: water is removed rapidly; these soils are commonly coarse-textured or very shallow.
  • Well drained: water is removed readily but not rapidly.
  • Moderately well drained: water is removed somewhat slowly during some periods of the year.
  • Somewhat poorly drained: water is removed slowly, so the soil is wet at a shallow depth for significant periods during the growing season.
  • Poorly drained: water is removed so slowly that the soil is wet at shallow depths periodically during the growing season, or stays wet for long periods.
  • Very poorly drained: water is removed so slowly that free water stays at or very near the surface for much of the growing season.
  • Subaqueous: the soil lies under water.

Why drainage changes across a field

Drainage classes describe how often and how long a soil is wet, and a slow class has a cause: somewhat poorly drained soils commonly have a slowly permeable layer, a high water table, water seeping in from higher ground or nearly continuous rain[2]. The same field can hold several classes, which is why the map shows a patchwork rather than one color per county.

From a rise to a hollow: the seasonal water table (dashed) sits closer to the surface downslope, and water stands in the low spot.

What drainage looks like in a soil pit

You can often see drainage in the soil itself. University of Kentucky Extension lists blue-gray or white soil, moss, standing water and a sour smell as signs of a poorly drained spot[3], and it traces 80 to 90 percent of disease and insect problems in landscape plants to poorly drained soil[3].

Three soil cores: brown all the way down, mottled where the soil is wet part of the year, and gray-blue under a dark surface where the water table sits near the top.

To fix a wet yard, start with improving soil drainage; to see how close the water table comes at an address, use water table depth.

Drainage across the US

Acre-weighted across USDA’s drainage-mapped soil, the natural drainage classes split like this[1]:

57%10%Well
  1. Excessively drained: 3.0% of drainage-mapped acres
  2. Somewhat excessively drained: 5.1% of drainage-mapped acres
  3. Well drained: 57.4% of drainage-mapped acres
  4. Moderately well drained: 10.2% of drainage-mapped acres
  5. Somewhat poorly drained: 7.6% of drainage-mapped acres
  6. Poorly drained: 9.8% of drainage-mapped acres
  7. Very poorly drained: 6.8% of drainage-mapped acres
  8. Subaqueous: 0.0% of drainage-mapped acres
Share of USDA drainage-mapped acres in each natural drainage class
Natural drainage classShare of acres
Excessively drained3.0%
Somewhat excessively drained5.1%
Well drained57.4%
Moderately well drained10.2%
Somewhat poorly drained7.6%
Poorly drained9.8%
Very poorly drained6.8%

The most poorly drained states

States ranked by the share of their drainage-mapped acres that are poorly or very poorly drained, among states with at least 500 components carrying a mapped class[1]:

StatePoorly or very poorly drainedComponents
Florida66%18,370
Alaska48%22,164
Minnesota45%35,040
Louisiana42%7,587
Illinois28%23,604
Michigan27%35,198
Maine27%9,943
Iowa25%28,667
North Carolina25%15,315
Indiana24%17,760

Download the data: drainage classes (CSV), drainage by state (CSV). Aggregated from USDA SSURGO; data generated 2026-10-08. See the methodology.

Frequently asked questions

What do soil drainage classes mean?
USDA’s natural drainage class describes how fast water leaves the soil on its own, from excessively drained (water removed very rapidly) to very poorly drained (wet at or near the surface for much of the growing season)[2].
Which states have the most poorly drained soils?
By share of drainage-mapped acres, Florida leads at 66%, followed by Alaska and Minnesota and the other states in the table above[1].
What are the signs of poorly drained soil?
University of Kentucky Extension lists moss, standing water, a sour smell and blue-gray or white soil, and notes that plants on waterlogged soil can wilt as if they were dry[3].
How do I check drainage at my address?
Search the map above for USDA’s mapped class, which is the map unit’s typical class[1], then confirm on the ground with a perk test, which times how fast water drains from a hole[3].

Sources

  1. USDA NRCS, Soil Survey Geographic Database (SSURGO), via Soil Data Access
  2. USDA NRCS, Soil Survey Manual (Agriculture Handbook 18), Ch. 3: drainage classes
  3. University of Kentucky Extension, ID-237 Soil Percolation: A Key to Survival of Landscape Plants (2016)

Marko Visic · MPharm, BSc Physics · Last reviewed November 13, 2026