The Environmental Protection Agency is proposing to let oil companies continue to dump polluted wastewater on the Wind River Reservation in Wyoming. This includes chemicals that companies add to the wells during hydraulic fracturing, an engineering practice that makes wells produce more oil.

An discovered that the EPA was allowing oil companies to send so much of this contaminated water onto dry land that it was creating raging streams. At the time, there was a controversy within the agency over whether to keep allowing this practice, according to documents NPR obtained through a Freedom of Information Act request.

On Friday, the EPA will close the public comment period on for several oil fields on the reservations. The proposed permits include some additional restrictions, but would allow companies to continue releasing the water.