San Marcos utility customers were recently notified again that their tap water contained a potentially harmful chemical from flooding that occurred over nine months ago.
Quarterly water samples taken by Texas Commission on Environmental Quality personnel on Nov. 7, 2013, a week after the Halloween flood created more than 15 inches of rain in the Guadalupe River Watershed, showed a higher-than-recommended amount of trihalomethanes, a type of organic compound.
“We tried to get it out as soon as we knew about it,” said Jon Clack, assistant director of public services.
These chemical compounds are primarily the result of chlorine disinfection and are formed when the “chlorine combines with organic matter like decaying vegetation commonly found in lakes and rivers,” according to the Environmental Protection Agency.
Chlorine was used to disinfect the city’s surface water supply after the Halloween flood washed excess debris into it, Clack said.
More than 90 percent of the water used by San Marcos residents comes from Canyon Lake through the Guadalupe River to Lake Dunlap, Clack wrote in an e-mail. The remainder comes from the city's Edwards Aquifer groundwater wells.
City Spokeswoman Melissa Millecam said “this is not an ongoing problem,” a sentiment echoed by Clack, but it is the result of averaging quarterly water samples from eight sites.
Although multiple follow-up tests conducted in January through this month show the chemical to be under state and federal standards, the water sample location at 345 Champion Blvd. continues to exhibit slightly higher than recommended levels of trihalomethanes, Clack said.
Federal standards cap the annual average maximum level of trihalomethanes at 0.080 milligrams or 80 parts per billion.
The sample taken at the Champion Boulevard site following the Halloween flood was at 158 parts per billion, which boosted averages to 87 parts per billion for the fourth quarter of last year, as well as the first (86 parts per billion) and second (81 parts per billion) quarters of this year.
This is why the TCEQ again required the city to submit a new notice to its 27,000 customers last month.
San Marcos resident Lisa Coppoletta said she initially found out about this issue through a Facebook post and immediately went to the city’s website for more information.
However, the information Coppoletta was looking for, a press release, wasn’t there, she said. Therefore, the local environmental advocate wrote an opinion column in June for the Love Hays website.
Shortly after her op-ed was published, the city submitted a press release, Coppoletta said.
Coppoletta added that the city’s second notice was “more timely” than the first but wished there was more government transparency.
The TCEQ initially alerted the city of its levels of trihalomethanes at the end of May, Clack said. The first public notice was sent to customers with their utility bills sometime in June.
The city had been in contact with state environmental personnel before the initial notice was sent to customers, but the city did not know any of its water sampling sites were in violation until the end of May, Clack said.
This is the first time the city has not been in compliance, and officials will take steps to ensure it will never happen again by “flushing” the system’s pipes more frequently, he said.
“The longer (contaminants are) in the pipes, the more that’s going to form,” Clack said.
To put the numbers in perspective, Clack said one part per billion can be compared to one penny in $10 million.
“It’s extremely small quantities,” he said of the amount of trihalomethanes in the city’s water supply.
Clack said there is no need to find an alternative water source or purchase a filtration system.