Los Angeles’ industrial, farming and development history has left traces of contamination in the groundwater throughout the San Fernando and San Gabriel valleys, according to a new statewide water survey now under way. Unveiling some of the survey’s first findings, state scientists said Wednesday that they detected very low levels of chemicals in almost all of the 35 groundwater wells they tested throughout the region. The results were no surprise to water regulators, who regularly test the aquifer and then filter, treat or dilute groundwater to ensure it’s safe for people to drink from the tap. But the state survey is unique because it measured contaminants at very low levels – smaller than 1part per billion, similar to a single drop in a swimming pool – and found a wide range of new and known contaminants showing up in groundwater. Sampling began in 2004, and scientists are looking for an array of chemical solvents, pharmaceuticals, pesticides and radioactive isotopes. Officials from the U.S. Geological Survey presented preliminary results for the L.A. groundwater basin to water-quality officials Wednesday. They sampled 12 groundwater wells, approximately one every 10square miles in the eastern San Fernando Valley, Eagle Rock and communities at the base of the Verdugo Mountains – where groundwater is pumped. Twenty-three wells were tested in the San Gabriel Valley. The samples were conducted on water straight from the ground. Water is typically filtered, treated or diluted before it’s delivered to customers. Scientists found volatile organic compounds in 33 of the 35 wells tested. The most commonly detected solvent was tetrachloroethylene, or PCE, a chemical once routinely used in dry cleaning and manufacturing; PCE was found in 83percent of wells tested. A handful of wells showed volatile organic compounds above pollution limits. But water from those wells is treated or diluted before being served. Researchers also found very low levels of pesticides in 31 of the 35 wells. Results on whether pharmaceuticals were detected in drinking-water wells are not available yet. “This is not water that people get out of the tap in Los Angeles. If any well becomes an issue, we take it offline and don’t use it,” L.A. Department of Water and Power spokesman Joe Ramallo said. DWP officials weren’t surprised by the range of contaminants found in the region’s groundwater. They have seen the same trend, and it’s an issue they have struggled with for years, Ramallo said. “There is no doubt that groundwater as a viable resource in Los Angeles is threatened. That’s why we’ve taken an aggressive stand against polluters.” The San Fernando Valley basin provides about 15percent of L.A.’s drinking water. Over the years, however, pollution has jeopardized that crucial supply. The DWP and neighboring cities have been trying to clean up a legacy of contamination started in the 1940s when heavy industry, defense contractors and aerospace businesses set up shop along the rail lines in Glendale, Burbank and the eastern San Fernando Valley and spilled chemicals on the ground that seeped into the aquifer below. The U.S. Geological Survey will publish a full report on the sampling results later this year. The group is beginning water-well testing in the Santa Clara River groundwater basin next month. email@example.com (213) 978-0390 Information Survey results are not available online yet, but more information on the Groundwater Ambient Monitoring Assessment program is available at www.waterboards.ca.gov/gama. “This data can be used to characterize water quality long before problems arise,” said Kenneth Belitz, a research hydrologist with the U.S. Geological Survey. “It provides early awareness of constituents of concern.” Belitz said the survey is not an indicator of what people are actually drinking, but rather an assessment of the aquifer that supplies drinking water. The work is part of a 10-year, $50million study being conducted by the U.S. Geological Survey and sponsored by the California State Water Resources Control Board. Legislators ordered the analysis with the Groundwater Quality Monitoring Act of 2001, which sought to understand what is in California’s drinking water and how to address emerging pollution problems.