Canyon Lake is a census-designated place (CDP) in Comal County, Texas, United States. The population was 21,262 at the 2010 census. It is part of the San Antonio Metropolitan Statistical Area.The Canyon Lake CDP includes a number of small, unincorporated communities surrounding Canyon Lake, including Sattler, Startzville, Canyon City, Cranes Mill, and Hancock. Communities located on the fringes of the CDP are Fischer, Spring Branch, and Smithson Valley. According to the United States Census Bureau, the CDP has a total area of 156.9 square miles (406 km2), of which, 144.3 square miles (374 km2) of it is land and 12.6 square miles (33 km2) of it (8.04%) is water.