Traces of hexavalent chromium are widely found in the drinking water of millions of Californians, some naturally occurring and some from industries that work with the heavy metal.
The proposed standard is a major step in a decades-long effort to curtail the water contaminant made infamous by the movie Erin Brockovich, based on residents of rural Hinkley, California, who won more than $300 million from Pacific Gas & Electric for contamination of their drinking water.
Once finalized, the standard would be a first in the nation to specifically target hexavalent chromium.
Several hundred drinking water wells throughout the state exceed the State Water Resources Control Board’s proposed standard of 10 parts per billion. The highest levels were reported in parts of Ventura, Los Angeles, Yolo, Merced and Riverside counties. Residents of the low-income, mostly Latino city of Los Banos, for instance, are drinking water that contains three times more than the proposed standard would allow.
Water suppliers say the proposed standard will lead to substantially higher monthly rates for many residents, while public health experts and environmental advocates criticize it as not protective enough of people’s health.
“It’s not terrible, but it’s not acceptable,” Max Costa, professor and chair of environmental medicine at NYU School of Medicine, said of California’s proposal. Costa was an expert witness for residents in the Erin Brockovich case.
When it comes to hexavalent chromium in drinking water, he said, “The most acceptable level is none.”
Under the water board’s proposal, 10 parts per billion would be the maximum allowable amount in drinking water. It’s a minute amount, equivalent to about 10 drops of water in an Olympic-sized swimming pool. But it’s also 500 times greater than the amount California’s scientists deem a negligible cancer risk over a lifetime.
Under state law, the state must balance the health risk and the financial cost when setting drinking water standards.
Monday's proposal is a draft, released to solicit public comment before officially starting the regulatory process, which could begin by late summer. An official drinking water standard is unlikely to be finalized before 2024.
Until recently, the science was mixed on whether hexavalent chromium causes cancer when ingested, rather than inhaled. (Inhaling it has been a well-documented cause of lung cancer for workers for several decades.)
But in 2008, National Toxicology Program studies showed rats and mice that drank high doses of hexavalent chromium for two years developed oral and intestinal cancers. In addition, California state scientists who analyzed the scientific literature reported increased stomach cancer risk among people who work with hexavalent chromium.
Chemical industry representatives have criticized the studies, saying the rodents were drinking levels much higher than people are exposed to. Mice and rats are routinely given large doses to extrapolate the cancer risk to a larger human population that lives longer.
In 2011, California scientists set a non-enforceable public health goal for hexavalent chromium that is much more stringent than today’s proposal — 0.02 parts per billion. The amount was chosen because it poses a negligible, one-in-a-million lifetime cancer risk that is generally considered acceptable for environmental contaminants.
The water board’s proposal would pose a much higher risk — one cancer among every 2,000 people over a lifetime, according to the state’s risk assessment.
“I think we would all much prefer to be at a better protective level than one in 2,000 cancer cases,” said Darrin Polhemus, deputy director of the division of drinking water with the State Water Resources Control Board. “But the costs do impose a really high burden at the lower (standard) levels, and just couldn't strike that balance there. So, I wish there was a different scenario to paint.”
The limit is likely to be tested in court. It’s happened before: In 2014, California set a short-lived standard of 10 parts per billion. But in 2017, a judge overturned it, ruling that state regulators had failed to consider whether the rule would be economically feasible.
Hexavalent chromium, also known as chromium-6, is used in industrial processes such as metal-plating, stainless steel production and wood preservation. It also naturally occurs in certain California rocks and soil.
State data shows that 129 community drinking water systems serving more than 4.1 million people have reported hexavalent chromium levels above the proposed standard. In addition, 51 systems serving institutions and businesses — including 11 schools — and three water wholesalers exceed the proposed limit. (Some wells may no longer be supplying water to residents.)
The highest level reported by the state is in Ventura County, where one drinking water well was reported with 173 parts per billion — more than 17 times higher than the proposed standard.
Latino communities and those with larger populations of other people of color are more likely to have drinking water with average levels of hexavalent chromium above 5 parts per billion, according to Lara Cushing, a UCLA assistant professor of environmental health who conducted a recent study.
Current federal and California drinking water standards combine hexavalent chromium and its more benign alter ego, trivalent chromium, which is considered an essential nutrient. Federal drinking water standards cap total chromium at 100 parts per billion, and California at 50 parts per billion.
Once a standard is finalized, water suppliers must remove the chemical from drinking water to below 10 parts per billion or face penalties that could include fines of up to $1,000 a day.
They can treat the water at plants or at household taps through reverse osmosis or another technology, blend it with clean water, take contaminated wells offline or pipe water from another system.
The proposal gives water providers some time to comply, Polhemus said — two to four years after the rule’s adoption, depending on their size. In the interim, water providers that detect hexavalent chromium will be required to submit their plans and timeline for attaining the standard.
Domestic well owners — like those in the San Bernardino County town of Hinkley portrayed in the movie — are not covered by drinking water standards. Private well owners are generally responsible for testing and treating their own water.
The cost of treatment is likely to increase customer rates, although some water agencies might opt for a cheaper option, such as blending their water with cleaner sources.
Rates for the smallest water systems — fewer than 100 connections — could increase by around $38 per month if suppliers install treatment in households. Systems with between 100 and 200 connections may see hikes as high as $44 to $167 per month, based on installing reverse osmosis or other costly treatment systems, according to state estimates. The largest water providers, which can buffer the costs across all customers, could have monthly increases between 75 cents and $45.
State regulators couldn’t predict what funding will be available when a standard is eventually finalized, but said in general, state and federal programs help communities clean up their drinking water.
Some larger water providers are looking forward to the end of a drawn-out regulatory process.
“I've been hoping for it to be re-finalized for some time,” said Tarrah Henrie, manager of water quality for California Water Service, the third largest regulated water utility in the country. “It just gives us certainty.”
The utility has nearly 500 active wells around the state. Of them, 20 wells tested above 10 parts per billion hexavalent chromium. The wells are located in the Solano County town of Dixon, the Glenn County town of Willows and in two small water systems near Salinas.
Ten of the wells are being treated — in Willows, with the help of a state grant. Though rates increased slightly in Dixon, Henrie said, the company has been able to prevent customer rates from spiking by subsidizing residents there. Without the subsidy, customer rates in Willows and Dixon would have increased by 18 percent to 28 percent.
Los Banos in Merced County is bracing for the financial hit.
Rates could increase “exponentially,” said the city’s outside counsel Mary Lynn Coffee. Costs to treat water from 13 wells could run from $41.6 to $92.3 million, with annual costs running between $1.7 and $5.1 million, Coffee said, based on a 2015 assessment. The city’s water budget has averaged around $4.7 million for the last four years.
The 13 wells that serve the largely Latino city of around 45,000 people have average hexavalent chromium levels of around 29.8 parts per billion, three times higher than the proposed standard would allow. Los Banos residents earn on average about 60 percent of the state average, and California has categorized the city as disadvantaged.
Since all signs point to the hexavalent chromium being naturally occurring, “there is no polluter that would help contribute to the cost of cleanup,” Coffee said. “Disadvantaged communities are really in desperate need of state funding assistance if they're going to meet a new (limit) around the 10 parts per billion mark.”