"When a pipeline break in North Dakota spilled salty, toxic drilling wastewater into a tributary of the Missouri River last year, it was national news.

But it was only one of more than 640 oil and gas spills that affected groundwater or surface water in some way in 2015, according to a review of state and federal records by EnergyWire. Such spills can contaminate water with oil, salt, metals and even radiation.

At nearly 3 million gallons, the January 2015 pipeline break north of Williston, N.D., was the largest spill reported to have affected water. Most were far smaller. But 500,000 gallons of coalbed methane wastewater reached a small creek in southern Colorado in July 2015, and a 250,000-gallon spill from a West Texas well site in February 2015 reached the Pecos River."

Mike Soraghan and Pamela King report for EnergyWire August 8, 2016. [2]