A billion-dollar cleanup at one of Utah’s most popular recreation destinations is almost complete, and a new report hints at what might be in store. The U.S. Government Accountability Office spent a year auditing the Moab Mill Site, a Cold War-era uranium processing facility sandwiched between the Moab, the Colorado River and Arches National Park. …  The Moab Mill Site operator dumped processed rocks in an unlined tailings pond, which contaminated the surrounding groundwater with uranium and ammonia, threatening the nearby Colorado River. … As of this year, according to a report released Wednesday, the government has removed 16 million tons of tailings, loading them on rail cars at the Moab site and shipping them 30 miles away to a landfill near Crescent Junction specifically designed to house the tailings.