BISMARCK, ND – For about 40 years, state workers have been dumping saltwater left over from oil production on some North Dakota roads. That’s news to the health department, which wants the practice stopped, according to The Associated Press. The Transportation Department claims oil well wastewater — up to 10 times saltier than sea water — is a safe, effective, and cheap de-icer.

However, according to the Sierra Club, this type of ‘de-icer’ is potentially contaminated and can cause unknown harm to wetlands, streams, and water supplies.

Transportation spokeswoman Peggy Anderson said the state Health Department had approved the use of the salty wastewater for de-icing. But the health department’s water quality director, Dennis Fewless, said he hadn’t even heard about the practice until asked about it this week by The Associated Press.

Fewless said the wastewater pulled from oil wells may contain oil and chemicals from drilling operations.

“The bottom line is, we need to look to the future and look for better options and phase this process out,” Fewless said, as quoted by The Associate Press.