SACRAMENTO, CA: New study examines groundwater quality in North San Francisco Bay Region

September 8, 2010 (Water Tech)
New study examines groundwater quality in North San Francisco Bay Region

SACRAMENTO, CA, September 8, 2010 (Water Tech) — A U.S. Geological Survey (USGS) report prepared in cooperation with the California Water Resources Control Board found high concentrations of naturally occurring inorganic constituents — including arsenic, boron and lead — in about 14 percent of the primary aquifers in Napa, Sonoma and Marin counties, according to a press release.

Primary aquifers are those that supply public drinking water.

The USGS assessment analyzed untreated groundwater from wells, not water delivered to consumers through the tap. Regulatory benchmarks are enforced only for water delivered to consumers, the release stated.

Arsenic was detected above the Maximum Contaminant Level (MCL) of 10 parts per billion (ppb) in about 10 percent of the primary aquifers.

Boron was detected above the California Notification Level, a non-regulatory benchmark of one part per million, in about 4 percent of the primary aquifers.

Lead was detected at high concentrations in about 2 percent of the primary aquifers. The U.S. Action Level for lead is 15 ppb.

“The work done by the Priority Basin Project in the North San Francisco Bay Area is important because we are providing, for the first time, a quantitative assessment of the extent to which deep groundwater may have high concentrations of both natural and man-made constituents,” said co-author Dr. Kenneth Belitz, chief of USGS’ GAMA program. “This information can be used by managers to ensure that our drinking water supply remains safe.”