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City warns of elevated bacteria levels in San Marcos River


5:09 p.m. FRIDAY, MARCH 25 | The city of San Marcos has rescinded its warning about elevated E. coli contamination in a stretch of the San Marcos River after samples collected on Thursday were determined on Friday to have normal levels of bacteria.


2:36 p.m. FRIDAY, MARCH 25 | Elevated levels of E.coli bacteria have been detected in the San Marcos River between the Interstate 35 bridge and the confluence with the Blanco River.

Signs are being posted in the affected area notifying river users of the elevated bacteria levels and will remain until bacteria levels fall back to normal. Bacteria levels in the affected area are not high enough to warrant closing the river, but people using the river in the affected area do so at their own risk, city spokesperson Trey Hatt said this afternoon in a press release.

Results from monthly river samples taken just above and below the outfall of the wastewater treatment plant on Monday, March 21 showed elevated E. coli readings, but the wastewater treatment plant effluent showed E. coli readings well into their normal range. 

Separately, a wastewater spill was discovered and repaired during a routine maintenance check of city wastewater infrastructure on Tuesday just below the Interstate 35 bridge. The volume of the spill was estimated to be 2,000 gallons.

Samples were taken at additional points in the affected area of the river Wednesday to determine if there were additional areas of concern, and elevated E. coli levels were detected. Samples were also taken on Thursday, and results are expected this afternoon.

The city continues to investigate to find out if the spill near the Interstate 35 bridge was the sole contributor to the elevated bacteria levels, or if there are other sources to be found and fixed.