Oil companies in California produce more water than oil. In the San Joaquin Valley that also has created a problem: what to do with all of that unwanted water? In most cases that wastewater is injected back into the ground, deep below the aquifer. But in some cases, injections may have contaminated federally protected aquifers that could be clean enough for drinking water. The problem has been in the news for several years, but as KQED's Lauren Sommer reports, we still know surprisingly little about the scope of the problem. She joined us on Valley Edition to talk about her report and what it means for local residents, farmers and oil producers.