Hexavalent chromium, or chromium-6, has been found in two water supply wells located at 11926 Madrona St. on San Antonio’s far-Westside.
Hexavalent chromium, or chromium-6, has been found in two water supply wells located at 11926 Madrona St. on San Antonio’s far West Side. Credit: Bonnie Arbittier / Rivard Report

Linda Patillo remembers telling state environmental investigators around five years ago about the strange-colored water her son observed flowing off the River City Metal Finishing site at 12040 Potranco Rd. during heavy rains.

“It would be purple or green or yellow,” she said. “It was interesting.”

Patillo is secretary of the Coolcrest Property Owners’ Association, which represents the Coolcrest neighborhood of approximately 1,000 people on San Antonio’s far West Side, just south of the now-demolished plating plant that left traces of hexavalent chromium pollution in drinking water serving the neighborhood.

Although the concentration of hexavalent chromium in those wells is far under the legal limit, information from the Environmental Protection Agency, the State of California, and a senior scientist with chemical watchdog Environmental Working Group indicate it may pose an elevated cancer risk if consumed for many years.

When the metal plating business was in operation from 1994 to roughly 2002, it specialized in chrome, nickel, copper, brass, silver, gold, and aluminum etching, according to EPA documents.

The EPA recently added the site to its National Priorities List for further investigation and cleanup under its Superfund program.

In August 2013, investigators with the Texas Commission on Environmental Quality (TCEQ) removed containers of waste and demolished buildings left standing on what is now an empty lot.

The State also placed a restrictive covenant on the property so it can be used only for commercial and industrial purposes, according to the EPA.

Despite those early cleanup efforts, cyanide, lead, cadmium, copper, selenium, zinc, and two forms of chromium were left behind in soil and shallow groundwater below the site, according to the EPA. Chromium-6 has migrated even further underground, the agency said.

“Chromium contamination in the shallow groundwater aquifer appears to have migrated to the deeper Edwards Aquifer, the sole source of drinking water in this area,” the EPA wrote in a letter to the neighborhood association.

The now-demolished River City Metal Finishing is located at 12040 Potranco Rd. on San Antonio’s far West Side. Credit: Courtesy / Google Maps

In January, the EPA published a report that detailed tiny amounts of chromium-6 in the two Coolcrest wells.

The concentration in the wells is far below the legal limit under federal and state rules, what’s known as the maximum contaminant level. EPA investigators found concentrations of 0.232 parts per billion and and 0.194 parts per billion, respectively, in the two water wells.

For total chromium, the drinking water standard is 100 parts per billion. That’s around 500 times higher than the concentrations found in the neighborhood’s wells.

EPA webpages on chromium-6 discuss its acute toxicity in extremely high doses and its effect on skin, with links to allergic dermatitis. The EPA has also long considered chromium-6 a carcinogen when inhaled, though it has never formally recognized it as a carcinogen when ingested.

In 2008, the U.S. Department of Health and Human Services’ National Toxicology Program published the results of a study on the carcinogenic effects of a chromium-6 compound in drinking water. The two-year study found the substance caused oral cancer in rats and small intestine cancer in mice.

That led the EPA in 2010 to propose considering it a carcinogen when ingested, though the process was never finalized.

Still, in their January report, EPA investigators wrote that levels found in the wells were roughly four times higher than what they call a “cancer risk screening concentration benchmark” – 0.05 parts per billion.

That benchmark represents the probability of one excess case of cancer emerging in a population of 1 million people drinking the water, EPA spokeswoman Jennah Durant said in an email.

“Screening values are generally used to determine if additional investigation at a site is needed,” she wrote. “Adding the River City site to the [National Priorities List] will allow for additional investigation and a specific risk assessment.”

In an interview with the Rivard Report, David Andrews, a senior scientist with the Environmental Working Group, discussed the extreme range between the legal limit and the non-binding levels that regulators often will use as goals to guard against cancer risk.

“The implications there are relatively large when you’re looking at such different values,” Andrews said. “They’re based on completely different health endpoints. It’s the skin irritation versus the long-term cancer risk.”

Some states have adopted more strict chromium-6 standards than the EPA’s. In July 2014, the State of California established a legal limit of 10 parts per billion, 10 times lower than the federal limit.

That legal limit lasted only until May 2017, when the Superior Court of Sacramento County issued a judgement invalidating it. That came in response to a lawsuit by the California Manufacturers and Technology Association, among other plaintiffs.

California had also in 2011 adopted a non-binding public health goal of 0.02 parts per billion, lower than the EPA’s value. Like the EPA’s cancer screening benchmark, it represents the probability of one excess cancer case in 1 million people.

With shifting and contradictory health information, Andrews said his group has been trying to educate U.S. consumers about the differences between the goal and the limit. In 2016, the group tested tap water from 35 cities and found low levels of chromium-6 in 31 of them.

“Oftentimes utilities and companies will say if the contaminant is below the legal limits, then it’s safe,” Andrews said.

That’s what happened when Patillo contacted SouthWest Water Company, which owns the small water system that serves the Coolcrest neighborhood.

In a conference call last September, EPA officials told SouthWest Water employees that the water was safe for all household uses, according to an email exchange Patillo shared with the Rivard Report.

“We directly asked the EPA representatives if the water was safe to drink, cook with, and bathe in,” Gary Gold, a director of operations at SouthWest Water’s western Texas office, wrote in the email. “They responded with yes to all aspects of using the water.”

Gold also shared with Patillo an Aug. 12, 2016, letter from TCEQ project manager Adrienne Love saying the levels were not only below the legal limit but also below another threshold her agency uses as a guide to protect public health.

“Your sample results were compared to the TCEQ Texas Risk Reduction Program health-based protective concentration levels, which represent safe levels,” Love wrote. “No chemicals of concern were detected at concentration levels above their [protective concentration levels].”

The most recent tests of the water in May 2017 also detected no chromium, according to TCEQ data. However, the type of test used cannot detect chromium concentrations below 0.5 parts per billion, Durant said in an email.

SouthWest Water’s environmental health and safety manager, Tim Williford, did not return a phone message seeking comment.

For residents who might be concerned, Andrews suggested installing a reverse-osmosis filter, which can run about $200. Ion-exchange filtration pitchers that cost about $30 would also work, he said.

Bottled water is not the answer, Andrews said. Since many bottled water sources are the same as municipal drinking water, it could contain chromium-6 as well.

Brendan Gibbons

Brendan Gibbons

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