The San Antonio watershed (HUC 18060009) covers an area of approximately 2,734 square miles in south-central Texas. It includes the city of San Antonio and several smaller communities. The hydrology of the watershed is influenced by the Balcones Fault Zone, which creates a divide between the Edwards Aquifer to the east and the Rio Grande watershed to the west. The watershed receives an average of 30 inches of rainfall per year, with the majority occurring during the summer months. Snowpack is not a significant factor in this region. The watershed encompasses several surface water bodies, including the San Antonio River and its tributaries, as well as several reservoirs, such as Canyon Lake and Medina Lake. The reservoirs serve as important sources of drinking water for the surrounding communities. The climate in the San Antonio watershed is characterized by hot summers and mild winters, with occasional freezes. Recent trends indicate an increasing frequency of drought conditions, which have significant impacts on water availability in the region.