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Indicator A4 (Hydrogen Sulfide) is most likely to occur in salt marshes and other very wet ecosystems.

Field Indicators of Hydric Soils in the United States

A Guide for Identifying and Delineating Hydric Soils, Version 9.3

Cover of Field Indicators of Hydric Soils in the United States, Version 9.3.

"Field Indicators of Hydric Soils in the United States" was developed by NRCS soil scientists in cooperation with the U.S. Fish and Wildlife Service; the U.S. Army Corps of Engineers; the Environmental Protection Agency; various regional, state, and local agencies; universities; and the private sector. Included in this publication are the hydric soil indicators approved by the NRCS and the National Technical Committee for Hydric Soils (NTCHS) for use in identifying, delineating, and verifying hydric soils in the field. 

Hard copies of Version 9.0 are available from the distribution center. Version 9.3 is available online only.

Order a hard copy from the NRCS Distribution Center.

Download Field Indicators of Hydric Soils in the United States

Field Indicators of Hydric Soils in the United States, Version 9.3 (9.7 MB)
Errata for Field Indicators of Hydric Soils in the United States, Version 9.0, February 2026 (114.61 KB)

 

Recommended Citation

United States Department of Agriculture, Natural Resources Conservation Service. (2026). Field Indicators of Hydric Soils in the United States, Version 9.3.

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