Article courtesy of Ellen Knickmeyer | January 26, 2015 | San Jose Mercury News | Shared as educational material
SAN FRANCISCO (AP) — One in four household water wells in parts of California’s Central Valley contains potentially harmful levels of uranium, a U.S. Geological Survey study said.
One in four domestic wells in the eastern Central Valley, and one in five monitoring wells in agricultural areas of the valley, showed uranium at levels that would be unacceptable for public water systems, the study found.
The study, which calls the levels of uranium found in the California farm region’s private wells surprising, is part of a report rounding up nationwide testing of 6,600 wells that draw from the country’s main water aquifers.
“Private water wells tend to have a higher rate of it because they’re shallower,” Kostyrko said of uranium.
Public water systems can treat for uranium by diluting the groundwater with fresher water, but that can be expensive, Jurgens said. Private well owners typically don’t have that option, Jurgens said.
In the Central Valley’s Kern County, environmental-health director Donna Fenton confirmed problems with uranium levels in some private water wells, but was unable to immediately say if it was an increasing problem, as the study suggested. Testing for uranium is required as part of getting a drilling permit for a new water well, Fenton said.
Roughly two-thirds of all groundwater used in California is pumped up in the Central Valley, primarily for farmers. A drought, now entering its fourth year, has sharply increased the dependence of farmers and other users on groundwater. The national report, released late last week, cut off in 2010, meaning it does not include any effect from increased use of groundwater during California’s drought.
The Central Valley regularly ranks among the country’s worst areas for water and air pollution. The U.S. Geological Survey study also noted that 29 percent of domestic water wells tested in the Central Valley showed nitrate levels — typically produced by fertilizer runoff from fields — are above the maximum acceptable amount. That compares with 4 percent nationwide.
The kind of permeable, unconfined aquifers found in the Central Valley are especially vulnerable to contamination, the study noted.
Nationwide, 22 percent of wells sampled showed at least one contaminant at a level high enough to cause concern, the study said.