Field Indicators and Literature Summary for an Arid Southwestern Aquatic Resource Delineation at Twentynine Palms, CA

In 1994, the U.S. Marine Corps Air-Ground Combat Center (MCAGCC) in Twentynine Palms, CA, requested a delineation of their aquatic resources. MCAGCC is located within the central Mojave Desert, where annual precipitation levels are insufficient to produce the three parameters typical of wetlands (i.e. vegetation, soils, and hydrology). At MCAGCC, two major aquatic resource types other than wetlands regulated under the Clean Water Act (CWA) as Waters of the United States (WoUS) were delineated at the planning-level scale. As part of the delineation process, new and unreported hydrology field indicators observed in the field were evaluated within the context of 48 literature citations. These hydrology indicators were used in the delineation process for identifying the Ordinary High Water Mark (OHWM) under Section 404 of the CWA for WoUS. A report was generated as a result of the study conducted at Twentynine Palms.