Executives with the oil-and-gas industry who are eager to remove oil from sedimentary rock throughout the West, including in Colorado, won’t be happy when they read the latest report from Congress’ investigative arm, the Government Accountability Office. The GAO concludes that if states allow the oil-shale industry to begin operations, a water dilemma will arise—namely, competition with downstream demands in cities and towns, even for fish, notes the Grand Junction Sentinel.

The amount of oil in the Green Formation of Colorado, Utah, and Wyoming likely has the equivalent of as many as three trillion barrels trapped in the rock, up from prior estimates of two trillion. The GAO report “sends a warning flag to those seeking to develop shale,” says David Abelson of Western Resource Advocates, which monitors oil shale, adding that diverting large quantities of water to large-scale projects would “forever change the social and economic foundation of Western communities.”

The report also focuses on oil shale in the Piceance Basin of northwest Colorado and in the Uintah Basin of northeast Utah, as well as the evolving technology surrounding oil shale. Some extraction processes would require one barrel of water, or 42 gallons, to reap one barrel of oil. Other methods would use one dozen barrels of water to get one barrel of oil. The average amount is five barrels of water used per barrel of oil, points out the Denver Business Journal. Growing communities are likely to need the water in coming years. A population boom in the Yampa, White, and Green river areas in Colorado, for instance, is anticipated, with the population, along with water consumption, there expected to rise threefold by 2050.