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Effects of Groundwater Development on Uranium: Central Valley, California, USA

January 1, 2010

Uranium (U) concentrations in groundwater in several parts of the eastern San Joaquin Valley, California, have exceeded federal and state drinking water standards during the last 20 years. The San Joaquin Valley is located within the Central Valley of California and is one of the most productive agricultural areas in the world. Increased irrigation and pumping associated with agricultural and urban development during the last 100 years have changed the chemistry and magnitude of groundwater recharge, and increased the rate of downward groundwater movement. Strong correlations between U and bicarbonate suggest that U is leached from shallow sediments by high bicarbonate water, consistent with findings of previous work in Modesto, California. Summer irrigation of crops in agricultural areas and, to lesser extent, of landscape plants and grasses in urban areas, has increased Pco2 concentrations in the soil zone and caused higher temperature and salinity of groundwater recharge. Coupled with groundwater pumping, this process, as evidenced by increasing bicarbonate concentrations in groundwater over the last 100 years, has caused shallow, young groundwater with high U concentrations to migrate to deeper parts of the groundwater system that are tapped by public-supply wells. Continued downward migration of U-affected groundwater and expansion of urban centers into agricultural areas will likely be associated with increased U concentrations in public-supply wells. The results from this study illustrate the potential longterm effects of groundwater development and irrigation-supported agriculture on water quality in arid and semiarid regions around the world.

Citation Information

Publication Year 2009
Title Effects of Groundwater Development on Uranium: Central Valley, California, USA
DOI 10.1111/j.1745-6584.2009.00635.x
Authors Bryant C. Jurgens, Miranda S. Fram, Kenneth Belitz, Karen R. Burow, Matthew K. Landon
Publication Type Article
Publication Subtype Journal Article
Series Title Ground Water
Index ID 70042435
Record Source USGS Publications Warehouse
USGS Organization California Water Science Center

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