Republicans on the House Energy and Commerce Committee sent a letter Tuesday to Environmental Protection Agency administrator Gina McCarthy seeking answers on why the agency abruptly turned over an investigation into whether the natural gas extraction process called fracking contaminated groundwater in Pavillion, Wyo., to state agencies.

The letter also sought documents regarding two similar cases in Dimock, Pa., and Parker County, Texas. “In all three cases, EPA asserted its jurisdiction to investigate alleged water contamination only to later abandon the investigation and let the states take control,” the Republican lawmakers noted.

The EPA’s actions in all three cases have puzzling. Environmentalists have claimed that the EPA caved to industry pressure. Today’s letter showed Republicans find the agency’s actions inexplicable too.

The lawmakers are seeking answers to a series of questions relating to these decisions as well as contemporaneous documents between the EPA and the states.

“We are really just hoping to better understand their decision-making and how it will apply to the broader, more comprehensive study” the EPA is planning on fracking, a Senate GOP staffer told the Washington Examiner.

The letter was signed Chairman Fred Upton, R-Mich., and Reps. Joe Barton, R-Texas, Marsha Blackburn, R-Tenn., Tim Murphy, R-Penn., Michael Burgess, R-Texas, John Shimkus, R-Ill., and Ed Whitfield, R-Ky.