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.
“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 concentration in the wells is far below the legal limit under federal and state rules, what’s known as the maximum contaminant level.
For total chromium, the drinking water standard is 100 parts per billion.
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.
“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.
In July 2014, the State of California established a legal limit of 10 parts per billion, 10 times lower than the federal limit.
California had also in 2011 adopted a non-binding public health goal of 0.02 parts per billion, lower than the EPA’s value.
“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.
“Your sample results were compared to the TCEQ Texas Risk Reduction Program health-based protective concentration levels, which represent safe levels,” Love wrote.