Rosillo Creek begins at 29°31' N, 98°22' W, approximately 0.5 miles north of FM 1976, in Northeastern Bexar County, Texas, within the city limits of Windcrest, Texas, and flows southwestward for eighteen miles through the Rosillo Creek Basin, with an elevation ranging from 265 meters above sea level, to 155 meters above sea level. The vegetation of the basin is mostly mesquite trees and grasses.