With the help of hydraulic fracturing, energy companies have doubled North Dakota's oil production in the past two years. But the oil boom has come at a cost: these companies are spilling and leaking oil and wastewater at an increasing rate. Here we map all the releases that energy companies reported to state authorities from 2009-2011. Related Story »

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Data processing by Andrew Long. Source: North Dakota Department of Mineral Resources. Notes: The data does not include an unknown number of cases of illicit dumping. Also, state officials say company estimates of spill volume are often inaccurate. Zeros may indicate that nothing was released, or it may indicate that the company simply did not know how much spilled.