CT ECO Basic Data Guide

Hydric Soils

Example of Hydric Soils


Hydric soils are defined as soils that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part. Under natural conditions, these soils are either saturated or inundated long enough during the growing season to support the growth and reproduction of hydrophytic vegetation. For additional documentation including a description of the map legend for Hydric Soils, refer to the CT ECO Complete Resource Guide for Hydric Soils.

All soil information included in the CT ECO maps and map viewers is from the Natural Resources Conservation Service (NRCS) Web Soil Survey (WSS), which is based on information originally published on the set of Soil Survey quarter quadrangle maps that cover Connecticut.


Hydric soil have a number of agricultural and nonagricultural applications. These include assistance in land-use planning, conservation planning, and assessment of potential wildlife habitat. A combination of the hydric soil, hydrophytic vegetation, and hydrology properties define wetlands as described in the National Food Security Act Manual (Soil Conservation Service, 1994) and the Corps of Engineers (COE) Wetlands Delineation Manual (Environmental Laboratory, 1987) and COE Regional Supplements for the Clean Water Act Section 404 permit program. Section 404 requires a permit from the COE for the discharge of dredged or fill material into the waters of the United States, including wetlands. Therefore, an area that meets the hydric soil definition must also meet the hydrophytic vegetation and wetland hydrology definitions in order for it to be correctly classified as a jurisdictional wetland.

Use Limitations

This data set is not designed for use as a primary regulatory tool in permitting or siting decisions, but may be used as a reference source. This is public information and may be interpreted by organizations, agencies, units of government, or others based on needs; however, they are responsible for the appropriate application. Federal, State, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions that they make. The Natural Resources Conservation Service will not perform any evaluations of these maps for purposes related solely to State or local regulatory programs.

Dataset Information

  • Status - This information is updated as needed. The previously published county soil surveys (published between 1962 and 1981) are superseded by this official soil information. County soil surveys are for historical use only.
  • Date of Data - The original data was collected from published surveys from 1962 to 1981, field mapping from 1985 through 2001 and additional attribute documentation to 3/23/2007.
  • Map Scale and Accuracy - 1:12,000 (1 inch = 12,000 feet). Minimum delineation is 3 acres in size.

Additional Documentation

  • Hydric Soils - CT ECO Complete Resource Guide
  • Soil map unit GIS Metadata - Contains technical documentation describing the Soil map units data and the data sources, process steps, and standards used to collect, digitize, and store this information in a geographic information system (GIS).
  • Soil interpretation GIS Metadata – Contains technical documentation describing the data table that defines soil interpretation such as Hydric Soils, Inland Wetland Soils, and Potential for Subsurface Disposal Systems. This lookup table is related to the soil map unit data and used to create the various soil interpretations included in CT ECO.
  • CT Soil Map Units Dominated by Hydric Soils lists, defines and describes hydric soils.
  • For additional technical documents on field indicators and hydric criteria see Hydric Soils.
  • 1987 Corps of Engineers Wetlands Delineation Manual is a Federal delineation manual used in the Clean Water Act Section 404 regulatory program for the identification and delineation of wetlands.


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