A causeway built by the Gallaudet Aircraft Company (1916) allowed truck access to the island for building a seaplane manufacturing factory. Arnold Cove today is a silted in marsh with only a narrow, winding channel, exiting North toward Chepiwanoxet Beach that is no longer navigable. The cove is quickly being populated by "Phragmites" reed grass, an invasive species that can grow over 15' high and quickly crowds out natural habitats. If uncontrolled "Phragmites" may totally fill the entire cove in several decades.