A SAWS crew member digs a canal to channel spilled sewage near Weidner Road under Wurzbach Parkway. The spill was caused by grease, rags, and debris from nearby homes and businesses. Credit: Courtesy / San Antonio Water System Facebook

More than 2 million people rely on the Edwards Aquifer for their drinking water, but what many don’t know is that between 2012 to 2017, more than 900,000 gallons of sewage spilled over its recharge zone.

That’s according to five student researchers from Texas State University who found that public agencies could drastically improve how they collect data about critical threats to the resource.

“I don’t think the data was hidden, but it was definitely not easy to find,” said Justin Williams, one of the students who developed the research. “Probably the most time-consuming part of the whole project was just getting the raw data that we needed for it.”

Williams – along with fellow students Haylea Elliff, Jasi Mitchell, Joseph Berenji, and Alexandra Thompson – used data they obtained from the Texas Commission on Environmental Quality (TCEQ) to create an interactive map that shows sewage spills over the Edwards Aquifer recharge zone from 2012 to 2017. The online map is open and accessible to the public.

These spills can at times threaten private wells that tap the Edwards Aquifer for drinking water, said Annalisa Peace, director of the Greater Edwards Aquifer Alliance, which commissioned the report.

“The impacts to … their household wells could be serious,” she said. “It’s a problem because people don’t typically get their wells tested very often. There hasn’t been some kind of a comprehensive effort when there is a spill to get the wells tested.”

Sewage spills don’t only threaten the Edwards Aquifer. They also contribute to high bacteria counts in San Antonio’s rivers and streams. All of  San Antonio’s urban waterways are considered too polluted with bacteria to be considered safe for swimming, according to the TCEQ.

The map covers the 25 counties of the TCEQ’s San Antonio and Austin regions. In this area, the largest sewer provider is the San Antonio Water System, the municipally owned utility that provides water and sewer service to 1.7 million people in the San Antonio area.

SAWS is also under court order to upgrade its sewer system to stop leaks. In 2013, the utility agreed to a 10-year, $1.1 billion consent decree with federal environmental regulators to study and improve its system.

The Rivard Report discussed the students’ map with Jeff Haby, SAWS vice president of production and treatment, spokeswoman Anne Hayden, and technical planner Kevin Taylor.

They recognized the value of visualizing the spill data, but were able to find a few data points that appeared to have been mapped incorrectly. Taylor said that might be a result of the data changing hands.

“We are the primary source of the data,” Taylor said. “It’s our spill. We go out there, collect it, and transmit it to the TCEQ. Whenever you request data from an outside source, the information can degrade. You can start questioning what level of confidence you have in that data.”

SAWS  issues press releases about spills in volumes that exceed 50,000 gallons and occur over the recharge zone or within a half mile of a drinking water well and for spills elsewhere equalling 100,000 gallons. The utility reports all spills of one gallon or more to the TCEQ but does not issue public announcements about them.

SAWS has not published its own map of spills, though its staff posts reports in pdf form that detail the volume of every spill, likely cause, and cleanup efforts.

The utility has also posted a graph on sewer.saws.org that organizes sewer spills by cause from 2010 to 2016. In dry years, the most common causes are structural failures and clogs with leaks and debris. The static graphic does not include raw numbers for each type of spill.

The SAWS site also includes a map of sewer projects that features a project description, budget, and construction timeline.

“We work very hard to be transparent,” Hayden said. “We’re improving the way we report, and we think we’re making huge progress in it.”

In their final report, the students said they filed an open records request to TCEQ for the data, which cost $43.23 and came to them as a spreadsheet and scanned copies of handwritten notes. About 11 percent of the data, the students said, was unusable.

“There’s a definite need for drastic improvement,” Williams said of the data collection and distribution methods of some public agencies in Texas.

Peace expects SAWS’ spills to decline as the utility continues to upgrade its system.

“I know SAWS is doing a good job now because of the consent decree,” Peace said.

The team of student researchers sees an opportunity to support those public agencies that could use more sophisticated technology in their data collection methods.

“They do have options out there, but they haven’t made the investment yet,” Williams said of public agencies’ use of technology to gather and share data.

“That’s what I’m hoping to see going from here, is not just the information on the spills but helping to get the data collected in a more transparent way.”

Emily Royall

Emily Royall is the Rivard Report's former data director.

Brendan Gibbons

Brendan Gibbons is the San Antonio Report's environment and energy reporter.