Monday night's storm sent 430,000 gallons of diluted wastewater overflow into the San Marcos River.
According to the City of San Marcos, rainwater entering the wastewater system triggered an overflow into the river Tuesday morning. The spill happened east of I-35 near the main lift station at 502 River Road.
The overflow was mostly rainwater, further diluted by river flow, said Jon Clack, assistant director of public services for the city.
Officials said they did not anticipate any negative environmental effects from the overflow.
The line where the overflow occurred is undergoing repairs; it is the same site that saw an overflow of 800,000 gallons of wastewater and rainwater Jan. 25.
An estimated 2.23 inches of rain were recorded at San Marcos Municipal Airport during the storm.