WASHINGTON, July 13 -- Great River Hydro LLC, Westborough, Massachusetts, has submitted a public comment letter to the U.S. Department of Transportation Federal Aviation Administration endorsing the agency's notice of proposed rulemaking under Section 2209 of the FAA Extension, Safety, and Security Act of 2016. The company, which owns and operates hydroelectric generation facilities across New England, outlined challenges posed by unauthorized unmanned aircraft systems near its critical infras  more