(Continued) Historically, spring water from the Edwards Aquifer is the source of the San Antonio River. As the City of San Antonio has grown over 300 years since the Spanish colonial settlements, the Edwards Aquifer has been the city’s primary source of drinking water. The level in the aquifer is frequently drawn below the artesian level resulting in the headwater springs running dry, including the Blue Hole and the San
The Blue Hole and many of the smaller springs are now protected in the nature preserve Headwaters Sanctuary, established by the Sisters of Charity of the Incarnate Word in 2006. The Sanctuary consists of several acres surrounding The Blue Hole and 53 additional acres of urban forest. Unlike the rivers in the Texas Hill Country, which are facing water quality degradation from municipal wastewater treatment plants (WWTPs) and substandard septic systems, the San Antonio River is largely dependent upon recycled water from municipal WWTPs for its environmental flows. Without treated recycled wastewater there would be a risk of there being no water in the San Antonio River.
Stormwater runoff, both urban and rural, is the greatest threat to biological health in the San Antonio River Basin. The runoff is not cleaned at a treatment plant before being discharged into the environment. Pollutants like oil, grease, metals, bacteria, sediment, fertilizers, pesticides, pet waste, and thermal pollution accumulate on the surfaces. During rains, runoff carries the pollutants to area creeks and rivers. Stormwater runoff prevents creeks and rivers from meeting primary, and occasionally secondary contact recreation standards during and immediately after rain events. Stormwater runoff also brings floating trash into the river.