State and federal limits guide local water agencies to filter out certain chemicals and minerals to meet safety standards and protect public health.
Hexavalent chromium, or chromium-6, is one of them. It’s a toxic metal and, if too much exists in a water system, it can cause negative health effects.
Hexavalent chromium can occur naturally in groundwater and is also a byproduct of industrial processes.
The state has set a non-enforceable public health goal for the metal at 0.02 parts per billion and claims anything above this could lead to carcinogenic effects.
“There could be an increased risk of cancer. It can result in reproductive damage or harm to your liver,” said Environmental Working Group (EWG) Senior Scientist Tasha Stoiber.
The EWG is an organization that does research on things like drinking water pollutants. The group just released an interactive map showing levels of hexavalent chromium sampled in drinking water systems across the U.S.
It shows samples of the City of San Luis Obispo’s water between 2014 and 2015 registering 4.37 parts per billion of hexavalent chromium.
Stoiber said the sample is a snapshot in time from those years, so the map doesn’t necessarily show current levels.
“But, given that there was a detection of hexavalent chromium there, there’s a good indication that there is contamination for that specific water source or water system,” Stoiber said.
Jason Meeks is San Luis Obispo’s Water Treatment Plant Supervisor. He said hexavalent chromium is certainly a concern in general, but the EWG’s map could easily be misinterpreted.
He said the samples shown on the map came from a single well that provided about two percent of the San Luis Obispo's water and it has since been turned off.
“We really didn’t need that water and we figured that was the safest bet and the best for our citizens,” Meeks said.
Meeks said city residents should not be concerned about their water. He said every sample that has been taken since then shows no detectable amount of hexavalent chromium.
“I one hundred percent stand behind our product as completely safe to drink,” Meeks said.
Stoiber said the EWG is only concerned about levels of hexavalent chromium above 0.02 parts per billion as that could cause negative health effects over a lifetime of exposure.
Click here to view San Luis Obispo’s annual water quality reports.
