New state standards for contaminant levels in drinking water put more than half of Davis’ drinking wells over the limit for hexavalent chromium, a heavy metal contaminant that occurs naturally in soils around Davis.
The new regulations, which go into effect on July 1, set the limit at 10 ug/L; Davis wells measured chromium-6 levels ranging from negligible to a high of 37 ug/L in a West Davis well, as of the most recent August 2013 measurements.
The city ran a biological pilot study to determine the best methods for reducing the contaminant. While the trial successfully decreased hexavalent chromium levels by 91 percent, the water department is mainly focused on switching Davis to surface water sources by 2016 through the Davis-Woodland Clean Water Agency. No cost estimates for reducing the contaminant to state standards are available.
“It may be at some wells, it’s worth putting in treatment, but we haven’t actually made those determinations yet,” said Stan Gryczko, the Davis waste water treatment plant superintendent.
Previously, chromium-6 was grouped within the state’s general chromium limit of 50 ug/L, which includes trivalent chromium, an essential nutrient. California is the first state to enact a specific limit for the contaminant, which can cause cancer when inhaled and has been linked to cancer when ingested.
The state is providing some funding for cities and regions to help with mitigation costs. The Davis-Woodland project will receive about $111 million in loans from the Safe Drinking Water State Revolving Fund.
Meanwhile, the county has begun drafting a proposal to require water testing during property sales. Martha Daschbach and her husband bought a $1.3 million property just north of the Davis city limits in 2005. In 2008, she discovered nitrate levels in her well effectively made the water non-potable; tests for chromium-6 came back at 46 ug/L as well.
“We assumed there were certain limitations in place, assumed we would have potable water,” Daschbach said. “We’re not stupid, but we’re somewhat trusting.”
While she freely admits she is trying to get her property reassessed and her taxes lowered, Daschbach said she has been urging Yolo County officials to pass a disclosure ordinance since 2010.
“At minimum, I didn’t want this to happen to somebody else,” she said.
The preliminary draft requires real estate agents to release information about nitrate, arsenic and coliform, said Leslie Lindbo, the county’s director of environmental health. The department is considering adding hexavalent chromium, but is consulting with Realtors and other stakeholders before submitting a draft to the Board of Supervisors.
Changing the disclosure laws requires an overhaul of the entire well ordinance, and Lindbo cited this as the main reason it could take until January 2016 to enact.
— Reach Elizabeth Case at [email protected] or 530-747-8052. Follow her on Twitter at @elizabeth_case