USGS to present initial findings of groundwater study

Scientists from the U.S. Geological Survey will discuss their initial findings from a comprehensive study of untreated well water in the central Sacramento Valley at a meeting Friday, March 9, in Oroville, CA.

The meeting, conducted by the State Water Resources Control Board and the USGS, is set for 1 p.m. to 3 p.m. at the Butte County Board of Supervisors chambers, 25 County Center Drive, Oroville. An agenda and map are available at the State Board's Web site.

From June to August 2006, USGS scientists collected samples from 71 public-supply, irrigation, domestic, and monitoring wells in portions of Butte, Colusa, Glenn, Sutter, Tehama, Yolo and Yuba counties to test for a large number of man-made and naturally occurring constituents. While some compounds were detected, all were at ultra-low concentrations - far below the health-based maximum contaminant levels (MCLs) set by state and federal guidelines.

A total of 19 volatile organic compounds (VOCs) were detected in 35 percent of the well water sampled, and pesticides were found in about 56 percent of the wells. The detections were at fractions - from one-tenth to nearly one-ten-thousandth - of the MCLs.

This study was designed to characterize groundwater quality in the aquifer systems in the central Sacramento Valley. It did not evaluate the quality of water delivered to consumers. After withdrawal from the ground, water is typically treated or mixed to maintain water quality. The study was conducted by the USGS and funded by the State Water Resources Control Board as part of the Groundwater Ambient Monitoring and Assessment (GAMA) Program, implemented with the cooperation of local water agencies.

The non-regulatory GAMA program is testing well water in every major groundwater basin in California over a 10-year period.

"The ability to detect the presence of man-made and naturally occurring compounds in groundwater wells at ultra-low concentrations is important for the protection of our water resources," said Dr. Ken Belitz, GAMA Program Chief Scientist. "Our goal is to understand how these compounds are transported from the landscape and into the aquifer system."

The USGS serves the nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.

Scientists from the USGS's California Water Science Center are leading the GAMA study. The center, based in Sacramento, has more than 130 scientists who bring a broad range of scientific disciplines to the study of modern water management issues. For more on the center, visit our Web site at http://ca.water.usgs.gov/.

USGS news releases are posted at http://www.usgs.gov/newsroom/default.asp.
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