The U.S. Coast Guard is considering a proposal that would allow natural gas drilling companies to transport wastewater from the process via barge. If the rule is approved, it could send these hazardous materials down the Ohio River.Hydraulic fracturing—or fracking—is when gas drillers inject large quantities of water and chemicals into a well to break up shale rock and extract natural gas. But once the fracking is over, companies are left with millions of gallons of contaminated water to dispose. Usually it’s transported across the country to disposal sites via trucks. But now the Coast Guard is considering letting companies send it down the nation’s rivers on barges.Carlos Diaz is a spokesman for the Coast Guard. He says if the proposal is approved, the transportation of fracking water will follow very strict guidelines.“If this goes through, they need to follow those rules,” he said. “And us as Coast Guard, we’ll enforce those standards and we’ll review those standards and maintain a regulatory role on transportation of materials.”Hazardous materials are already moved by barge every day, but because fracking wastewater isn’t one uniform substance—the composition varies from company to company—it’s not currently permitted.But environmental groups are still concerned about the potential effect the plan could have on waterways. Tim Joice of the Kentucky Waterways Alliance says the potential damage from a barge spill to waterways is greater than a similar accident on the roadway.“If there’s a spill and it goes directly into the water, you’re talking about immediate uptake by fish, potentially, you’re talking about potentially killing a lot of fish,” he said. “Somehow that’s going to have to be remediated. And if not, you’re talking about potentially polluting a significant amount of drinking water for millions of Americans.”Joice says he is in favor of one part of the proposal, which would require gas companies to disclose the chemicals in their fracking wastewater before the material is transported.The proposal is open for public comment until November 29.