Subsurface Atlas
Look up the USDA SSURGO soil map unit at a U.S. address and explore components, horizons, texture, drainage, HSG, hydric ratings, Ksat, restrictions, and water-table indicators.
Ready to use Subsurface Atlas?
Free to use with no account. Queries official U.S. Census and USDA soil-data services.
Confirm a Census-matched point on a draggable map before resolving the surrounding USDA SSURGO polygon.
Review map-unit components, percentages, horizons, texture, drainage, hydrology, restrictions, and missing values.
See survey area, map-unit key, retrieval details, methodology, and source links without an invented risk score.
Understand the mapped soil context for a U.S. property
Subsurface Atlas turns a street address or selected map point into a readable USDA soil-survey profile. After you confirm the location, the app performs a point-in-polygon lookup, identifies the surrounding SSURGO map unit, and presents every reported component instead of reducing a mixed map unit to a single soil label.
What the soil profile includes
- Map-unit identity: survey area, map-unit name, symbol, and source key.
- Component composition: named soils and their reported percentage of the mapped unit.
- Soil horizons: layer depths, texture, sand/silt/clay values, saturated hydraulic conductivity, and other available properties.
- Water behavior: hydrologic soil group, drainage class, flooding, ponding, hydric rating, and survey water-table indicators.
- Physical limitations: restrictive layers and linear extensibility data where USDA reports them.
A transparent lookup path
- The U.S. Census Geocoder matches a complete address; TIGERweb supports broader place searches.
- You verify the result and can move the pin to the intended point.
- USDA Soil Data Access identifies the SSURGO polygon containing that coordinate.
- The map unit is joined to its component, horizon, restriction, monthly-condition, and aggregated attribute records.
- The interface keeps missing values distinct and displays the source context needed to interpret the result.
Use survey data as context, not certainty
A USDA map unit can contain several major and minor soil components. The component with the largest percentage is not guaranteed to occur beneath a particular house, garden, driveway, or drain field. Subsurface Atlas is useful for early property research, landscaping questions, and understanding mapped conditions, but site-specific decisions still require qualified local professionals and field testing.
Continue with the guide to USDA SSURGO map units or learn how to read drainage, HSG, hydric, and Ksat values before interpreting a profile.
Frequently Asked Questions
Does Subsurface Atlas identify the exact soil beneath a house?
No. It identifies the USDA SSURGO map-unit polygon at the selected point and shows the components associated with that mapped unit. Conditions at a specific square foot can differ and require field investigation.
Can I use the result instead of a septic perc test or geotechnical report?
No. The lookup is for research and preliminary context. It is not a soil test, septic percolation test, wetland delineation, groundwater measurement, foundation analysis, or geotechnical investigation.
Where does the data come from?
Address and place matching use public U.S. Census Geocoder and TIGERweb services. Soil polygons, map units, components, horizons, restrictions, and hydrology attributes come from USDA NRCS Soil Data Access and SSURGO.
What happens when USDA has no value for an attribute?
Subsurface Atlas labels the value as not reported rather than replacing missing data with a misleading zero.