Dr. Holleran is currently working on a book about irrigation canals in the urban landscapes of the American West. He completed a statewide historic context report on canals and ditches for the Colorado State Historic Preservation Office, which will become a statewide Multiple Property nomination to the National Register of Historic Places.
He practiced for twelve years in as a partner in Everett · Clarke · Holleran Associates in Providence, Rhode Island, a planning, architecture, and landscape architecture firm working mainly on preservation projects. His public service has included chairing the Landmarks Preservation Board in Boulder, Colorado; and serving on the board and chairing the Public Policy committee of Colorado Preservation, Inc., a statewide preservation advocacy group. He is a board member of the national Recent Past Preservation Network and of the Heritage Society of Austin.