Drilling Down:The Community Consequences of Expanded Oil Development in L.A. This new report offers testimony from Angelenos living with the consequences of L.A.'s underregulated oil industry. Too little is known about the effects of expanded and unconventional oil-extraction techniques when there's drilling in L.A.'s backyards. L.A. is the largest urban oil field in the country and 70% of its active oil wells are located within 1500 feet of a home or school or hospital. Residents report health hazards, lack of information disclosure and a regulatory system that doesn't work.