KQED (June 13, 2013)

A growing demand for milk and cheese in China has the potential to bring California’s beleaguered dairy industry back to life – and with it, renewed concern about its damaging effects on the environment.

California dairies have been implicated in the pollution of groundwater.  Research has shown that nitrogen produced by cow waste can seep through soil into groundwater, contaminating water sources and, in some cases, making the water undrinkable. 

For instance, dairy manure, which is the largest source of animal manure in California, accounts for more than 200,000 tons of nitrogen every year, much of which ends up in groundwater, according to research by Thomas Harter, a hydrologist at UC Davis.

Nearly 10 percent of public water wells in California have more nitrogen than the government deems acceptable, while in some areas, more than one-third of private wells exceed that level, according to the UC Davis study.