U.S. Geological Survey

Madera County Groundwater Polluted

California desert aquifers used for drinking water have high levels of inorganic elements, including arsenic and boron


     The U.S. Geological Survey reports that inorganic elements - arsenic, boron, fluoride, and five other inorganic elements - have been detected at high concentrations in 35 percent of untreated groundwater used for public water supply in the deserts of southern California. In contrast, human-made organic chemical constituents and nitrate were found at high concentrations in less than 1 percent of the desert region’s aquifers.  READ MORE »

U.S. Geological Survey says benzene in California groundwater is mostly naturally occurring


    Benzene occurs infrequently in California public supply wells and comes predominantly from naturally occurring petroleum deposits deep in the ground, according to a study by the U.S. Geological Survey. Spills associated with underground fuel storage and above ground distribution systems have long been considered the main source of benzene in groundwater. This unique study finds that contamination most often occurs in older, brackish, groundwater located near naturally occurring deep underground oil and gas deposits.

    As part of a statewide study assessing groundwater quality, scientists analyzed untreated groundwater from wells, not treated tap water. Groundwater used for public supply is typically treated by water providers to ensure compliance with water quality standards. “This study illustrates the value of letting scientific facts speak for themselves when dealing with critical issues such as the frequency and potential sources of groundwater contamination,” said USGS Director Marcia McNutt.  READ MORE »

One in five private wells contaminated according to USGS



About 20% of untreated water samples from public, private, and monitoring wells across the nation contain concentrations of at least one trace element, such as arsenic, manganese and uranium, at levels of potential health concern, according to a new study by the U.S. Geological Survey. 

"In public wells these contaminants are regulated by the U.S. Environmental Protection Agency, and contaminants are removed from the water before people drink it," said Joe Ayotte, USGS hydrologist and lead author on the study. "However, trace elements could be present in water from private wells at levels that are considered to pose a risk to human health, because they aren’t subject to regulations.  In many cases people might not even know that they have an issue."   READ MORE »

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