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Hollister officials are concerned about the city’s potable water after it tested above the state’s maximum contamination level for chromium-6, a known cancer-causing element. However, officials said at a Feb. 9 Hollister City Council special meeting that residents do not need to boil their water or take corrective action at this time.
“The key message we want to convey is that water is safe to drink,” said City Manager Ana Cortez, who took over the top administrator position on Feb. 2.
Boiling water does not eliminate chromium. However, it can be done through a reverse osmosis or specialized filters.
The water contained a running annual average of 13.4 parts per billion (referred to by the state as micrograms per liter), which exceeds the state’s 10 parts per billion threshold.
Public Works Director Javier Hernandez noted that the city must address the chromium-6 levels and inform the public of the exceedance because the state has become stricter.
“It’s not necessarily that the water level is getting worse,” Hernandez said. “It’s just that testing is becoming more stringent.”
Councilmember Rolan Resendiz requested that staff review previous water test results to confirm whether the current chromium-6 levels are consistent. He also suggested bringing in a third-party company to conduct additional tests.
“I want to make sure that, just to calm people down and to have factual, scientific data that we bring in a nonbiased third-party environmental expert,” he said.
According to 2012-2022 data from the State Water Resources Control Board, those two wells have a 10-year concentration average of 13.7 parts per billion and 12.9 parts per billion, respectively. The Well on Nash Road, which Hernandez said tested under the limit, averaged 12.7 parts per billion during the same time period.
Hernandez said multiple samples collected between March and December 2025 from the wells at Bunderson Road and South Street exceeded the state’s limit. Additional tests, he said, were required to confirm the exceedance and notify the public.
Hernandez told the City Council one well tested at 13 parts per billion and the other “11 [or] 12.”
The city is required by state law to notify the community when its water tests above the maximum level for chromium-6.
According to Cortez’s letter, which was provided at the meeting and expected to be distributed to the community, one part per billion is similar to one drop of water in an olympic-size swimming pool.
“At this point, we have the data that shows regardless of where we tested in 2025, the result was the same and consistent,” Cortez said. “Now we’re able to say ‘yes, we need to deal with this situation.’”
Hernandez said the plan is to infuse additional treated surface water into the groundwater to dilute the level of chromium-6. He said the city needs state approval before implementing its plan.
Though Cortez told the City Council it wasn’t known if the levels of chromium-6 were caused by nature or another source, her letter says it’s believed to be naturally occurring.
The State Water Resources Control Board adopted the existing limit for chromium-6 in April 2024, 15 years after the California Environmental Protection Agency identified the element as carcinogenic.
According to the board’s website, prior to October 2024, the chromium-6 limit was less than 50 parts per billion.
According to its website’s most recent data, the concentration of chromium-6 between 10 and 20 parts per billion was recorded in 25 counties, including San Benito County, between 2012 and 2022.
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