Aspen conducted ground truthing and prepared new detailed vegetation maps for a twenty-three mile section of the Lower Colorado River between Mexico and the United States. Utilizing GIS, Aspen biologists compared existing vegetation data to determine the changes in riparian composition, including potential increases in invasive salt cedar populations and loss of cottonwood willow habitat over time. Habitat on this stretch of the Lower Colorado River provides nesting habitat for a number of sensitive birds including the Southwestern willow flycatcher and Yuma clapper rail.