Denver can't tell if it's collecting all it should from concessions sold at its Red Rocks Amphitheater and the Denver Coliseum, a new audit found. "Weak oversight" of inventory and the way cash is handled at the venues present a risk of theft and other security issues, says Denver Auditor Tim O'Brien. Denver Arts & Venues, the agency operating the city-owned cultural facilities, needs to better monitor its contract with concessions vendor Aramark Sports and Entertainment, which sells food, beverages and other items, O'Brien said in a statement. "They risk losing profits owed to the city," he said. Over the past three years, the city received $37 million from Aramark - a division of Philadelphia-based Aramark Corp. Read more on Colorado Springs Gazette