The Orange County Water District, which serves 2.5 million county residents, expects to see nearly a third of the 200 groundwater wells in its service area shut down by year’s end because of the presence of toxic PFAS, a chemical family linked to cancer, liver and kidney damage, low birth weight and other health problems.

Nine of those wells have already been closed and 32 more are expected to be closed in coming weeks as state regulators continue to lower acceptable thresholds for the toxins, according to district officials. As many as 31 additional wells could be shut down after testing is expanded later this year.