SALT LAKE CITY (AP) — As colleges grapple with the coronavirus, institutions across the country are turning campus sewage into a public health tool. At least two schools in Utah and Arizona have quarantined hundreds of students after tests showed the presence of genetic material from the virus in wastewater. Experts say it can be an inexpensive way to monitor people who may not even know they are sick yet. But it’s still imprecise measure for now, and some at Utah State University were disconcerted they didn’t know about the monitoring before their quarantine. Still, as outbreaks batter colleges, officials say wastewater monitoring holds serious promise as an early detection system.