This map service is an information surface representing the dominant class within the soil map unit polygon for flooding frequency probability. Each component (and therefore soil map unit polygon) falls into one of the following classes according to NRCS: None, Very rare, Rare, Occasional, Frequent, and Very frequent. The class belonging to the component that makes up the highest percentage of the map unit is reported by the map service. Another service exists for flooding frequency class which reports the most frequent class in the soil map unit. The concept is similar but for some purposes knowing the most frequently flooding component may be the most useful piece of information to know about soil map unit drainage class.
Esri is providing NRCS SSURGO content here without modification except for some cartography and publishing necessary to facilitate esri user access to these data. Of course, esri will continue to update this information as new editions of the SSURGO dataset are published by NRCS.
This map service is a representation of the NRCS SSURGO data table MUAGGATT, field FLODFREQDCD. The map service will display at scales between 15,000 and 600,000, but the intended scale of the data is 1:24,000. It is based entirely on the US Natural Resources Conservation Service SSURGO polygon dataset, mapped for every part of the United States that has come under survey. Some parts of the United States have not yet been mapped, and in a sense the SSURGO dataset is a seamless collection of individual soil survey maps rather than a single map for the whole United States. As a result, there may be inconsistencies between adjacent surveys because surveys may have been compiled in different decades and with slightly different methods and staff.
The map service is being served to you from a service in the amazon cloud. The map service is published in unprojected geographic space, in coordinate system WGS84. Because the map is published unprojected, it can be projected dynamically to order into the projection of your choosing. This means you can use the map service in any map, not just a "web mercator" projection. This also may mean it will take a second or two to draw your map to order. We welcome your comments on the speed and convenience of this map service.
For best results, this map service is designed to be shown over relief with about 50% transparency. We also recommend for context using the US Hydro Reference Overlay available from arcgis.com here.