Runoff is the most significant contributor to water quality degradation and biggest threat in the San Antonio River Watershed. Water that goes into storm drains is not treated before it reaches water bodies. This water is known as stormwater runoff or non-point source pollution.
The biggest non-point source pollution concern in the San Antonio River Watershed is elevated levels of E. coli bacteria. Numerous creeks do not meet primary contact recreation criteria set by the State. San Antonio River Authority scientists have seen a correlation between storm events and elevated bacteria levels in the river.