County soil summary
Soil types in Olmsted County, Minnesota
The most widespread soils are Downs, Tama and Racine; the most common drainage class is well drained (62% of the land), and typical topsoil pH is 6.5.
- Well or moderately well drained
- 77% of land · state 41%
- Typical topsoil pH
- 6.5 slightly acidic · state 6.5
- Septic fields very limited
- 92% of land · state 91%
- Subject to flooding
- 12% of land, any frequency · state 4%
Most common soils in Olmsted County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 39% of the mapped land; 95 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| Downs | 16.5% | Well drained | 6.2 |
| Tama | 5.2% | Well drained | 6.5 |
| Racine | 3.1% | Well drained | 6.8 |
| Rockton | 3.1% | Well drained | 6.2 |
| Channahon | 3.1% | Well drained | 7.3 |
| Garwin | 2.8% | Poorly drained | 6.5 |
| Floyd | 2.7% | Somewhat poorly drained | 6.7 |
| Timula | 2.4% | Well drained | 7.0 |
What this means
What the soils in Olmsted County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in Olmsted County is slightly acidic: pH 6.5 (most land between 6.2 and 7.0), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 97% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (59% of the land).
77% of the land is moderately well to excessively drained, which suits most garden plants.
For your lawn and yard
On 71% of the land, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.
A seasonal high water table comes within 18 inches of the surface on 23% of the land, often in spring. Basements, sump pumps and lawns in low spots feel it first.
For a septic system
For conventional septic absorption fields, NRCS rates 92% of the land in Olmsted County very limited, 7% somewhat limited and 0% not limited.
That is close to the state as a whole (91% very limited).
Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.
Flooding is mapped on 12% of the land (5% occasional, 7% frequent).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Drainage
How long the soil stays wet
The most common drainage class is well drained (62%). 77% of the land is moderately well drained or better, compared with 41% across Minnesota.
Show as a table
| Category | Olmsted County | Minnesota |
|---|---|---|
| Excessively drained | 3.5% | 3.1% |
| Somewhat excessively drained | 0.6% | 3.9% |
| Well drained | 61.6% | 20.3% |
| Moderately well drained | 11.0% | 13.7% |
| Somewhat poorly drained | 10.5% | 12.3% |
| Poorly drained | 10.2% | 20.7% |
| Very poorly drained | 1.8% | 22.1% |
| Not rated | 0.8% | 4.1% |
Septic absorption fields
NRCS rating for conventional drain fields
The rating looks at the soil from 24 to 60 inches deep: permeability, depth to a seasonal water table or bedrock, flooding and slope. “Very limited” means at least one feature is unfavorable enough that a conventional field is hard to make work.
Show as a table
| Category | Olmsted County | Minnesota |
|---|---|---|
| Not limited | 0.0% | 0.0% |
| Somewhat limited | 7.0% | 4.4% |
| Very limited | 92.1% | 91.3% |
| Not rated | 0.9% | 4.3% |
Rain, runoff and water table
Hydrologic soil group, flooding, seasonal water table
Hydrologic soil group
How fast rain soaks in when the soil is already wet. Group A soaks in fastest, D slowest.
Show as a table
| Category | Olmsted County | Minnesota |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 3.9% | 9.5% |
| B: moderate infiltration | 24.3% | 12.3% |
| C: slow infiltration | 44.4% | 16.9% |
| D: very slow infiltration (clayey, shallow or wet) | 4.6% | 4.4% |
| A/D: D as is, A if drained | 0.1% | 13.9% |
| B/D: D as is, B if drained | 16.1% | 14.0% |
| C/D: D as is, C if drained | 5.6% | 24.7% |
| Not rated | 0.9% | 4.3% |
Flooding
Show as a table
| Category | Olmsted County | Minnesota |
|---|---|---|
| No flooding | 87.8% | 92.4% |
| Rare or very rare | 0.3% | 0.2% |
| Occasional | 4.9% | 1.3% |
| Frequent or very frequent | 6.5% | 2.4% |
| Not reported | 0.6% | 3.7% |
Seasonal high water table
Show as a table
| Category | Olmsted County | Minnesota |
|---|---|---|
| Within 18 inches at some time of year | 22.5% | 52.0% |
| 18 inches to 3.3 feet | 4.6% | 15.0% |
| Deeper than 3.3 feet or none reported | 72.4% | 29.6% |
| Not reported | 0.6% | 3.3% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 6.5 (slightly acidic); 80% of rated land falls between 6.2 and 7.0. Median topsoil organic matter is 3%.
Show as a table
| Category | Olmsted County | Minnesota |
|---|---|---|
| Strongly acidic (below 5.5) | 0.0% | 7.0% |
| Moderately to slightly acidic (5.5–6.4) | 44.2% | 27.3% |
| Near neutral (6.5–7.3) | 52.9% | 32.0% |
| Alkaline (7.4 and up) | 1.6% | 15.2% |
| Not reported | 1.3% | 18.6% |
Texture
Show as a table
| Category | Olmsted County | Minnesota |
|---|---|---|
| Sandy | 1.9% | 11.2% |
| Loamy (loam, silt loam and similar) | 96.8% | 66.1% |
| Clayey (40%+ clay) | 0.0% | 2.2% |
| Organic (muck or peat) | 0.3% | 16.2% |
| Not reported (rock, urban land, etc.) | 1.0% | 4.3% |
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
- Olmsted County, Minnesota (FIPS 27109): 417,695 acres of mapped land, 1,905 acres of open water excluded. State comparisons pool all mapped land in Minnesota.
- Method
- Shares are by mapped land area: each map unit’s acres in the county times each soil component’s percentage. Open water is excluded. Topsoil values use the first mineral horizon of each component. Full methodology.