Medina Valley, also known as the Medina River Valley, is an area in south central Texas containing the Medina River, Lake Medina, and the Medina Dam. It serves to drain the Balcones Escarpment of the Texas Hill Country and irrigate the fire contained therein. It is approximately 120 miles (190 km) long and is named for the Medina River. Natural features The geology of Medina Valley has been analyzed for some time, with a prominent feature being the Balcones Fault Zone. There are a number of flora and fauna species associated with the Medina Valley. Some of the species in and close to Medina Valley have their distributional range defined by the Medina Valley and/or the Balcones Fault. For example, the California Fan Palm, Washingtonia filifera occurs only in the western USA west of the Medina Valley and Balcones Fault. Counties in Medina Valley Bandera County, Texas, Eastern Medina County, Texas, southwestern Bexar County, Texas, Atascosa County, Texas Communities in Medina Valley Bandera, Texas Castroville, Texas Mico, Texas Rio Medina, Texas LaCoste, Texas Lakehills, Texas Lytle, Texas Pearson, Texas Somerset, Texas St. Hedwig, Texas Elmendorf, Texas Von Ormy, Texas Medina, Texas References Geological Society of America. 1967. Bulletin: Geological Society of America, v. 78, nos. 7-12, University of Michigan C. Michael Hogan. 2009. California Fan Palm: Washingtonia filifera, GlobalTwitcher.com, ed. Nicklas Stromberg Line notes Regions of Texas