The University of Colorado Boulder will test the Campus Alerts text-messaging system on Tuesday, April 3, at noon in coordination with the annual flood siren testing, which begins Monday, April 2. “We’re raising awareness that the city of Boulder has the highest risk of flash flooding in Colorado because of its location at the mouth of Boulder Canyon, the number of people who live and work within the Boulder Creek floodplain, and the numerous other drainage basins running through the city,” said Lacey Croco, Ƶ-Boulder emergency manager.