Bacteria Conditions

The San Antonio River Authority (SARA) has been gathering water quality data in the San Antonio River Basin for approximately 40 years.

Currently, SARA collects water quality data at more than 50 locations within the basin, with weekly E. coli bacteria data collection at four sites along the San Antonio River.

The data has established that the most widespread water quality problem within the San Antonio River Basin is high levels of bacteria after rain events.

When rain falls directly on undisturbed natural surfaces, the soils, rocks, plants, and their root systems help 1) to filter out bacteria and pollutants before they reach our rivers, creeks, and streams and 2) to slow down the water as it travels through the basin, reducing the bacteria- and pollution-carrying sediments that are picked up and deposited into our water ways.

However, much of our rain falls on rooftops, streets, sidewalks, and other such surfaces—as well as on farm- and ranch-land where fertilizers, animal feed, and animal wastes are not adequately buffered from our rivers, creeks, and streams. This water, called runoff, carries bacteria and bacteria-promoting materials into our basin’s waterways.

Since this is a common problem in most basins within the state, recreationists who plan to do river-related activities in any basin should research that basin’s bacteria levels before engaging in contact recreation.

To plan for your San Antonio River Basin excursion, click on the line graph links to view a table that reflects the last 10 samples for E. coli bacteria at the four San Antonio River sites referenced above.

Site Number	USGS Station Name	Bacteria Collection Time	E. coli Bacteria Result
08188500	San Antonio River at Goliad, TX	05/09 at 9:16 AM	150 mpn Line Graph
08186000	Cibolo Creek near Falls City, TX	05/09 at 10:44 AM	560 mpn Line Graph
08183500	San Antonio River near Falls City, TX	05/09 at 11:27 AM	410 mpn Line Graph
08183200	San Antonio River near Floresville, TX	05/09 at 12:02 PM	5800 mpn Line Graph
08178565	San Antonio River at Loop 410, San Antonio, TX	05/09 at 12:50 PM	2900 mpn Line Graph
MPN—Most Probable Number (Colonies in 100 ml of water) NA—Data is not currently available