Soil survey area

Island of Maui, Hawaii

Survey Area HI980• Hawaii

The short version

The most common soil here is Rough mountainous land, on about 12% of the land. Very stony land and Hydrandepts come next.

About 94% of the land drains well; groundwater comes within two feet of the surface under 15% of it.

USDA rates 95% of the land very limited for a standard septic drain field, and 82% very limited for homes with basements. That means extra cost or special design, not that it can't be done.

Worth knowing: 3% of the land floods occasionally or more, and bedrock lies within 40 inches under 34% of it.

Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.

The ground underfoot

The soils you're most likely standing on

The biggest named soils in Island of Maui, Hawaii, each drawn five feet deep from its official USDA description, in its recorded colors.

Waiakoa

5% of the area

Very stony silty clay loam topsoil · well drained

Smooth and slightly sticky. Holds a lot of water.

Mollisols

Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.

The biggest mapped areas

The dominant drainage class is Well drained and the dominant hydrologic group is A (high infiltration, low runoff). The most common soil order is Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter. This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Island of Maui, Hawaii. Search your address to find the exact soil composition, drainage, and series details at your specific location.

Soil Map Unit	Acres	Drainage	Hydro Group	Dwellings	Septic
Rough mountainous land	54K	Well drained	B	Very limited	Very limited
Hydrandepts-Tropaquods association	46K	Well drained	A	Very limited	Very limited
Very stony land	34K	Well drained	A	Very limited	Very limited
Rock outcrop	17K		C	Very limited	Very limited
Rough broken land	16K	Well drained	C	Very limited	Very limited
Rock land	15K	Well drained	D	Very limited	Very limited
Waiakoa extremely stony silty clay loam, 3 to 25 percent slopes, eroded, MLRA 157	14K	Well drained	C	Very limited	Very limited
Puu Pa very stony medial silt loam, 15 to 50 percent slopes, MLRA 157	14K	Well drained	A	Very limited	Very limited
Honomanu-Amalu association	12K	Well drained	A	Very limited	Very limited
Lava flows, aa	10K	Excessively drained	A	Very limited	Very limited
Kamaole very stony silt loam, 3 to 15 percent slopes	7K	Well drained	B	Somewhat limited	Very limited
Hana very stony silty clay loam, 3 to 25 percent slopes	7K	Well drained	C	Somewhat limited	Very limited
Cinder land	7K	Excessively drained		Very limited	Very limited
Kailua silty clay, 3 to 25 percent slopes	6K	Well drained	B	Somewhat limited	Somewhat limited
Oanapuka extremely stony silt loam, 7 to 25 percent slopes	6K	Well drained	A	Very limited	Very limited
Amalu peat, 3 to 20 percent slopes, MLRA 164	5K	Poorly drained	D	Very limited	Very limited
Kaipoioi loam, 7 to 40 percent slopes	5K	Well drained	B	Very limited	Very limited
Keawakapu extremely stony silty clay loam, 3 to 25 percent slopes, MLRA 157	5K	Well drained	C	Somewhat limited	Very limited
Stony alluvial land	5K	Well drained	A/D	Very limited	Very limited
Puuone sand, 7 to 30 percent slopes	5K	Somewhat excessively drained	A	Very limited	Very limited

Soil Orders in This Area

The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.

Mollisols

Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.

Andisols

Volcanic ash soils — light, porous, and fertile. Excellent drainage, but low density can complicate foundations.

Aridisols

Dry-climate soils with low organic matter. Often have caliche layers that make excavation difficult. Low shrink-swell is good for foundations.

Inceptisols

Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.

Ultisols

Strongly weathered clay soils of the Southeast. Acidic and naturally low in nutrients. Clay subsoil can slow drainage.

Oxisols

Deeply weathered tropical soils. Nutrient-poor despite appearing lush. Rare in the continental US.

What This Means

Building & Foundations

About 82% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.

Septic Systems

About 95% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.

Gardening & Agriculture

Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.