By Tom Philpott, Mother Jones

In normal years, California residents get about 30 percent of their drinking water from underground aquifers. And in droughts like the current one — with sources like snowmelt from the Sierra Nevada mountains virtually non-existent — groundwatersupplies two-thirds of our most populous state’s water needs.

So it’s sobering news that about 20 percent of the groundwater that Californians rely on to keep their taps flowing carries high concentrations of contaminants like arsenic, uranium, and nitrate.

When farms sprouted up, they mobilized the once-stable uranium naturally present in the soil, and the toxic element leached into groundwater.

That’s the conclusion of a 10-year US Geological Survey study of 11,000 public-water wells across the state.

Read the whole story