Bismarck, N.D. (AP) Authorities say an oil executive accused of endangering drinking water in southwest North Dakota has reached a plea deal with federal prosecutors. Executive Drilling President Nathan Garber is slated to be sentenced on September 26th. The Montana man is charged with multiple felony counts of violating federal environmental laws. He faces more than 50 years in prison. Terms of the plea deal were not disclosed. The criminal charges against Garber are connected to a state case against Halek Operating, which was fined a record $1.5 million for illegally dumping more than 800,000 gallons of wastewater into a former oil well in Stark county. Authorities say Garber ordered the illegal dumping and told workers to tamper with the disposal well so it would pass a state inspection.