Changes in Hydric Soils Database Selection Criteria of the United States

The National Technical Committee for Hydric Soils (NTCHS), operating under the USDA Natural Resources Conservation Service (NRCS), has revised the database selection criteria used to identify hydric soils across the United States. The key change is the inclusion of subaqueous soils — soils found beneath permanent shallow water bodies — which were previously omitted from the hydric soils list due to gaps in the original selection criteria, not because they failed to meet the definition. This update is issued pursuant to 7 CFR 12.31, which requires NRCS to publicly notify changes to hydric soil selection criteria as referenced in USDA Miscellaneous Publication 1491 (June 1991) and the Federal Register notice at 60 FR 10349. The revision formally aligns the database with scientific knowledge that has evolved as subaqueous soils are now mapped in areas where they were previously uncharted. The practical impact on total hydric soil acreage is described as insignificant, since these soils have always met the legal and scientific definition of hydric soils. The update is administrative and technical in nature — correcting an omission in the selection algorithm rather than changing the underlying definition or regulatory standards for hydric soils. Wetland determinations, farm program eligibility under the Swampbuster provisions, and land use decisions relying on the official hydric soils list may now incorporate subaqueous soil components, improving the accuracy and completeness of wetland mapping nationwide.

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