How to Use Web Soil Survey

What is Web Soil Survey?

Web Soil Survey (WSS) is the U.S. Department of Agriculture’s Natural Resources Conservation Service (USDA NRCS) public website for exploring soil survey information. NRCS provides the application as a way to view information produced by the National Cooperative Soil Survey. The federal program’s data is organized around mapped soil areas and the properties and interpretations associated with them. WSS puts that material in an interactive map and report workflow instead of requiring you to start with a printed soil-survey book.

Much of the detailed map information is from the Soil Survey Geographic Database (SSURGO). SSURGO connects mapped soil areas to tabular descriptions of map units, their component soils, and related attributes. The map is designed for a chosen Area of Interest (AOI), so the acreage and percentages in a report describe that AOI. They are not automatically figures for a whole county or a particular tax parcel.

The tool is free to use for public soil information. It is an official USDA service; GroundLayers is independent and is not affiliated with, endorsed by, or operated by USDA or NRCS. Use the official site when you need the underlying government map, detailed data, or an NRCS-generated report. GroundLayers offers a separate, simpler address lookup for a quick public-data summary, but that is a different service and is not a substitute for WSS’s AOI reports.

WSS can help you ask questions such as: Which map units occur inside this drawn area? What soil properties are associated with those units? What does NRCS’s interpretation say for a selected land use? It cannot turn a regional soil map into a test of a specific spot in your yard. The distinction between a mapped area and a field-verified location matters throughout the workflow.

Before you start: decide what your AOI should include

An Area of Interest is the boundary WSS uses for its map and reports. Decide what question you want to answer before drawing it. A garden bed, a building site, a farm field, and a whole property are different AOIs. If you draw a large rectangle that includes a road, pond, neighboring land, or an area outside the parcel, those places may affect the map-unit list and the acreage summary. Draw as carefully as the map allows, and remember that an AOI is a research boundary you define in WSS; it is not a legal parcel boundary.

Have a street address or a recognizable nearby place ready to help locate the map. If you need to analyze a precise property outline, use a suitable boundary you are authorized to use and check whether the current application supports importing it. NRCS’s published guide describes rectangle and polygon drawing tools and an option to create an AOI from a shapefile or zipped shapefile. Imported boundaries still need to be checked on the map after they load.

NRCS says map-drawn rectangle and polygon AOIs are limited to 100,000 acres; a whole Soil Survey Area AOI is not subject to that same limit. A survey-area AOI is convenient for regional exploration, but it may be much larger than a property and answers a broader question. Don’t choose the largest available area just because it is easy to select: the chosen boundary controls which map units and totals appear in the results.

Step-by-step: use Web Soil Survey for an address

1. Open the official application

Start at the USDA NRCS Web Soil Survey site. The NRCS help page describes starting the application from its WSS home page. Let the map finish loading before choosing an area. If the map or a panel does not respond, try the application’s own help and troubleshooting links; NRCS notes that WSS has known problems and workarounds, and its availability can vary during maintenance.

WSS is arranged as a short sequence: define an AOI, view the Soil Map, explore soil information, and assemble a custom report. You can move between the main tabs after the AOI is ready, but the AOI is the key setup step. Soil Map and Soil Data Explorer results are tied to the area currently selected.

2. Find the location by address

In NRCS’s published Getting Started instructions, the left-side Quick Navigation panel includes an Address form. Enter the location details requested by that form and choose its View control to navigate the map to the place. Address search is a way to find the neighborhood on the map; it does not, by itself, define the area for a soil report. Treat any marker as a location aid, then inspect the map and move or zoom as needed.

If an address does not resolve cleanly, try a nearby road intersection, town, or a different address format. The published WSS guide also describes zooming and panning on the map and using other Quick Navigation choices, including State and County or Soil Survey Area. Use those options to get close, then visually confirm that the map is centered on the location you intended. Do not assume an address result is a surveyed property outline.

3. Define the Area of Interest

Once you have found the place, use an AOI rectangle or polygon tool to draw the area you want WSS to analyze. With a rectangle, drag around the site. With a polygon, click around its edges and finish the shape using the control described by the application. Zoom in enough to avoid including extra land, but keep the linework realistic: a small map-scale error can include or omit nearby map units. The exact tool icon and finish gesture are interface details, so check the live application’s contextual help if the control differs from NRCS’s published instructions.

You can also choose an entire Soil Survey Area through Quick Navigation and set it as the AOI. That is useful for learning what soils occur across a survey area, not for property-specific acreage. The AOI rectangle and polygon tools have the 100,000-acre maximum described above. If you have a mapped boundary file, NRCS’s guide describes importing a shapefile or zipped shapefile to make a multipart AOI; confirm the required file format and upload steps in the current app before relying on them.

Pause after drawing and inspect the outlined AOI. Check that it covers the land you intended and that it does not accidentally include a second parcel, a large stretch of water, or an adjacent field. If the outline is wrong, redraw or reset it before moving to the next tab. Every later map-unit area and percentage is scoped to this boundary, so correcting it now is easier than explaining mismatched totals later.

4. Open the Soil Map and inspect the legend

After the AOI is set, choose the Soil Map tab. NRCS describes this view as the soil map for your area, with map-unit information and descriptions. The colored or patterned areas represent map units. Look at the map and its legend together: the map gives you the spatial pattern, while the legend helps associate each mapped area with a symbol and name. Select a map-unit name to open its description when you need more context about what is grouped inside it.

The legend commonly reports each map unit’s symbol, name, acres in the AOI, and percentage of the AOI. Those columns refer to the boundary you just drew. A row with a larger acreage covers more of that AOI than a row with a smaller acreage; its percentage is its share of the area total. If the rows do not seem to represent the place you selected, return to the AOI tab and check the outline rather than assuming the soil layer is a parcel map.

A map-unit description is more detailed than the short legend name. NRCS map units may contain one dominant soil or a combination of major soils and miscellaneous areas. Descriptions explain the components and map-unit setting. A single polygon can therefore represent a landscape grouping rather than one uniform soil profile at every point. Read the description before translating a map color or name into a claim about a specific spot.

5. Explore properties, qualities, and interpretations

Choose Soil Data Explorer to explore information for the AOI. NRCS’s Getting Started guide describes inner sections for Suitabilities and Limitations for Use, Soil Properties and Qualities, and Soil Reports. The available folders and items depend on the question and the underlying data. Expand a category, choose a report or rating, set any requested options, and use the app’s View Rating or View Soil Report control. Ratings may be shown as a table and, for some interpretations, a color-coded map with a legend.

Start with a question, not with every table. For example, if you are exploring a building-related question, look for an interpretation that matches the feature and use you care about. If you need a measured or descriptive attribute, search Soil Properties and Qualities. The name of a report matters: two similarly named items can use different assumptions, depth ranges, or rating criteria. Read the report’s notes and definitions rather than treating its headline class as a recommendation for your specific project.

Interpretations are generated from soil-survey information and the criteria for the selected use. A favorable rating does not guarantee that a site will perform as expected; an unfavorable rating does not tell you, by itself, what engineering or management action to take. Ratings help you compare mapped soil units under stated criteria. For construction, septic, agricultural, drainage, or environmental decisions, bring the result to the qualified professional or local authority responsible for that decision.

6. Add useful items to the shopping cart and make a report

When you find a map, table, or report you want to keep, use its Printable Version or Add to Shopping Cart option when available. NRCS’s guide says the AOI soil map and map-unit list with descriptions are included by default in the cart; additional ratings and reports can be added. The Shopping Cart is identified as free in the published instructions. Review its contents before checking out so the finished document includes the material you need and not a long list of unrelated outputs.

The published instructions describe opening Shopping Cart (Free), choosing Check Out, and generating a combined PDF that can be retrieved immediately or later. NRCS advises keeping the cart to ten items or fewer for best results. If you need data files rather than a printable report, WSS also documents a Download Soils Data option for AOI data; those files are intended for technical use and may require GIS or database software. The exact names and placement of buttons can change, so verify the live app flow before following a control label that looks different.

How to read Web Soil Survey results

Map-unit symbols are identifiers, not soil grades

A map-unit symbol is the short label printed on the map and beside a legend entry. It links the mapped polygon to its longer map-unit name and description. The symbol is not a rating, a quality score, or a universal soil code that means the same thing everywhere. Read the symbol together with its survey-area context and map-unit name. Similar-looking symbols in different survey areas should not be assumed to refer to identical mapped units.

The map-unit name often includes a soil series or association, a surface texture, landscape position, or slope range. The name is useful shorthand, but it is not a complete description. The map-unit description may list multiple components and explain how they are distributed or associated. Component percentages describe the estimated composition of a mapped unit; they are not a guarantee that every point in that polygon contains that proportion of each soil.

Acres and percentages describe the selected area

“Acres in AOI” is the mapped area of a map unit inside the boundary you selected. “Percent of AOI” is that acreage divided by the AOI total, expressed as a percentage. If the AOI is a large farm field, the number describes the field outline you supplied; if you chose a whole Soil Survey Area, it describes that much larger region. It does not mean that a specific point on a parcel has been sampled or that a property boundary was verified by WSS.

Rounding can make displayed rows add to slightly more or less than the total shown. A map may also include nonsoil or water map units, or have areas where spatial soil data are not available. Read the table’s units and footnotes, and compare its total with the AOI description. If a field is blank, unavailable, or represented by a class rather than a measurement, don’t fill it in from another map unit or infer a precise value.

Property tables need their units, depth, and context

A soil property table can show a measured or estimated characteristic for map units or their components. Before interpreting a value, identify its unit, the depth or layer it refers to, the summary method, and any range or class shown. A depth interval is not the same as a single-point reading. A range describes variation represented by the survey; it is not a confidence interval for your exact lot. A categorical class is a grouped description, not a laboratory result from a sample taken at your address.

For a practical reading, take one row at a time: identify the map unit; read the column heading and unit; note whether the result belongs to the map unit or a component; then read the report legend or explanatory note. If the table says the map unit has several components, understand that the headline value can summarize or rate a mixed landscape unit. Compare neighboring rows only when the same attribute definition, units, depth, and AOI apply.

Suitability and limitation tables answer a narrower question than a general soil-property table. They apply an interpretation to a specified use, with classes and criteria defined by NRCS. A class should be read as the interpretation’s category under those assumptions. It is not automatically a pass/fail test, a permit decision, an engineering design, or an individualized recommendation. Open the report details and legend, and look for the factors that explain why a map unit received its rating.

Use the map, table, and description as one result

The map helps you see where a unit occurs; the table summarizes how much of your AOI it occupies; and the description explains what that mapped unit represents. None of those views is complete alone. A color on the map does not tell you the full component mix, while a table row does not show whether the unit is concentrated in one corner or spread throughout the site. Move between the three before writing down a conclusion.

Keep a record of the AOI boundary, the report name, and the date you generated the output. That makes it possible to distinguish a change in the selected area from a change in the available survey information or interpretation. If you share a PDF, include enough context that someone else can tell what AOI and report it represents.

Survey dates and limits to keep in mind

Soil surveys are made and revised area by area. The age, scale, detail, and available interpretations can vary between counties and even between neighboring survey areas. NRCS says its annual soils refresh updates soil survey data and interpretations once a year, but that does not mean every field observation or every mapped area was surveyed in the same year. Check the survey-area status and version information for the area you are using, and note the date you accessed the report. A recent website refresh does not make every underlying survey equally recent.

Soil maps are generalized representations of landscape patterns. Boundaries are drawn at a mapping scale and may include small inclusions of other soils that are too small or intermingled to show separately. A map-unit boundary is not a sharp physical edge you can necessarily locate on the ground. Properties can change over short distances, especially on complex terrain or disturbed urban land. The mapped class and its description are appropriate for understanding regional patterns, not for certifying the soil at a precise point.

WSS is not a substitute for an on-site investigation, soil sampling, geotechnical work, septic evaluation, or other required professional review. If you are making a high-consequence decision, use the map as background information and ask the relevant local office or licensed professional what fieldwork and standards apply. The appropriate next step depends on the decision: a garden question, construction design, and a permit review do not use the same evidence threshold.

Coverage and reports may also differ by data availability. NRCS notes that soil maps are generated when spatial soil data are available for the AOI. Some areas or specific interpretations may be unavailable, blank, or based on different data vintages. Treat “no result” as unavailable information, not as evidence that a soil condition is absent. Use NRCS’s status and help resources if you need to understand what is published for a survey area.