County soil summary
Soil types in Maui County, Hawaii
The most widespread soils are Molokai and Waiakoa; the most common drainage class is well drained (82% of the land), and typical topsoil pH is 6.3.
- Well or moderately well drained
- 88% of land · state 87%
- Typical topsoil pH
- 6.3 slightly acidic · state 6.0
- Septic fields very limited
- 91% of land · state 93%
- Subject to flooding
- 6% of land, any frequency · state 7%
Most common soils in Maui County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 46% of the mapped land; 69 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| Rough mountainous landGeneral soil group, not a named series | 12.0% | — | — |
| Very stony landGeneral soil group, not a named series | 8.4% | — | — |
| Rock outcropLand type, not a soil series | 7.1% | — | — |
| Very stony land, erodedGeneral soil group, not a named series | 4.4% | — | — |
| Molokai | 3.8% | Well drained | 6.5 |
| HydrandeptsGeneral soil group, not a named series | 3.6% | — | — |
| Rough broken landLand type, not a soil series | 3.4% | — | — |
| Waiakoa | 2.9% | Well drained | 7.0 |
What this means
What the soils in Maui County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in Maui County is slightly acidic: pH 6.3 (most land between 4.0 and 7.0), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 64% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silty clay loam (30% of the land).
88% of the land is moderately well to excessively drained, which suits most garden plants.
For your lawn and yard
Most land is in hydrologic groups B and C, where rain soaks in at a moderate pace.
For a septic system
For conventional septic absorption fields, NRCS rates 91% of the land in Maui County very limited, 6% somewhat limited and 0% not limited (2% not rated, such as urban land, pits or water).
That is close to the state as a whole (93% 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 6% of the land (2% occasional, 2% 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 (82%). 88% of the land is moderately well drained or better, compared with 87% across Hawaii.
Show as a table
| Category | Maui County | Hawaii |
|---|---|---|
| Excessively drained | 5.1% | 13.2% |
| Somewhat excessively drained | 0.6% | 3.1% |
| Well drained | 82.0% | 65.8% |
| Moderately well drained | 0.0% | 4.6% |
| Somewhat poorly drained | 0.0% | 0.6% |
| Poorly drained | 4.9% | 1.9% |
| Very poorly drained | 0.1% | 0.9% |
| Not rated | 7.3% | 9.8% |
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 | Maui County | Hawaii |
|---|---|---|
| Not limited | 0.0% | 0.2% |
| Somewhat limited | 6.2% | 5.1% |
| Very limited | 91.4% | 93.1% |
| Not rated | 2.3% | 1.6% |
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 | Maui County | Hawaii |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 24.1% | 29.2% |
| B: moderate infiltration | 24.6% | 18.3% |
| C: slow infiltration | 36.4% | 30.0% |
| D: very slow infiltration (clayey, shallow or wet) | 11.3% | 18.6% |
| A/D: D as is, A if drained | 0.8% | 0.2% |
| B/D: D as is, B if drained | 0.0% | 0.7% |
| C/D: D as is, C if drained | 0.0% | 1.0% |
| Not rated | 2.9% | 2.0% |
Flooding
Show as a table
| Category | Maui County | Hawaii |
|---|---|---|
| No flooding | 88.8% | 38.2% |
| Rare or very rare | 2.2% | 2.5% |
| Occasional | 1.9% | 3.6% |
| Frequent or very frequent | 1.5% | 0.6% |
| Not reported | 5.6% | 55.1% |
Seasonal high water table
Show as a table
| Category | Maui County | Hawaii |
|---|---|---|
| Within 18 inches at some time of year | 4.8% | 4.0% |
| 18 inches to 3.3 feet | 0.4% | 0.2% |
| Deeper than 3.3 feet or none reported | 89.2% | 40.8% |
| Not reported | 5.6% | 55.1% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 6.3 (slightly acidic); 80% of rated land falls between 4.0 and 7.0. Median topsoil organic matter is 3.5%.
Show as a table
| Category | Maui County | Hawaii |
|---|---|---|
| Strongly acidic (below 5.5) | 32.4% | 26.3% |
| Moderately to slightly acidic (5.5–6.4) | 16.4% | 20.5% |
| Near neutral (6.5–7.3) | 36.6% | 29.3% |
| Alkaline (7.4 and up) | 3.2% | 1.7% |
| Not reported | 11.4% | 22.3% |
Texture
Show as a table
| Category | Maui County | Hawaii |
|---|---|---|
| Sandy | 2.8% | 6.9% |
| Loamy (loam, silt loam and similar) | 64.3% | 59.0% |
| Clayey (40%+ clay) | 26.2% | 13.8% |
| Organic (muck or peat) | 3.4% | 1.6% |
| Not reported (rock, urban land, etc.) | 3.3% | 18.7% |
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
- Maui County, Hawaii (FIPS 15009): 754,389 acres of mapped land, 6,562 acres of open water excluded. State comparisons pool all mapped land in Hawaii.
- 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.