SURFICIAL FEATURES ASSOCIATED WITH PONDED WATER ON PLAYAS OF THE ARID SOUTHWESTERN UNITED STATES: INDICATORS FOR DELINEATING REGULATED AREAS UNDER THE CLEAN WATER ACT

Desert playas can be unambiguously identified in a geological context. However, identifying those portions of desert playas that are defined as either three-parameter wetlands or Waters of the United States (WoUS) in the Clean Water Act (CWA), and thus under the jurisdiction of Federal agencies charged with enforcing the CWA, is sometimes problematic. Although the WoUS definition specifically includes playas, the guidance for playa delineation is not as highly developed as that for wetlands. Delineating WoUS on desert playas involves determining the Ordinary High Water Mark. Field experience has demonstrated that the indicators for Ordinary High Water on desert playas have not been fully identified nor have they been associated with ponding that represents the limits of Ordinary High Water. This report discusses the distribution of indicators above, below, and at the Ordinary High Water Mark. Fifteen playa features are identified for possible delineation use and are rated for reliability and their relationship to the Ordinary High Water position.