Where the drilling and fracturing happened, water wells sometimes became contaminated. Waste pits leaked into aquifers. Large quantities of fresh water were used. Mountain glaciers and Wyoming valleys became shrouded in smog. Reports began to emerge that natural gas might cause almost as much greenhouse gas pollution as coal. Now the industry is at a crucial point. Even as the hard lessons have come into focus, the myriad opportunities presented by this vast fuel source have made its development inevitable.