Oil and gas companies used banned toxic chemicals near the Rocky Mountains

Oil and gas companies used banned toxic chemicals near the Rocky Mountains

A view of a drilling rig in Colorado. Oil and gas companies in the state once could obscure the chemicals they used in fracking as "trade secrets." Not anymore. (Photo by Getty Images)This story was originally published by Capital & Main. Colorado oil and gas companies used toxic chemicals prohibited under state law in operations involving dozens of wells on either side of the Rocky Mountains over at least the last 18 months, a Capital & Main in…