A watershed is a region or area that is drained by a river, stream, etc. Essentially, it is an area that all drains to 1 place. There are over 2,000 watersheds in the United States. Everyone lives in a watershed. That is why it is important for us to ensure that we reduce the pollution in storm water runoff.
In Bexar County, there are 6 watersheds:
Atascosa River Watershed
Cibolo Creek Watershed
Leon Creek Watershed
Medina River Watershed
Salado Creek Watershed
Upper San Antonio River Watershed
San Antonio River Basin Drain
Eventually, all watersheds (with the exception of Atascosa River Watershed) drain to the San Antonio River. The area these 5 watersheds encompass, along with the Lower San Antonio River Watershed which is just south of Bexar County, is called the San Antonio River Basin. The San Antonio River Basin drains to the Gulf of Mexico. So what we do here in Bexar County can ultimately affect everything from the San Antonio River to the Gulf of Mexico.