The collection consists of correspondence, engineering reports, blueprints, photographs, notes, and news clippings relating to Derleth's work as a consulting engineering on the Golden Gate Bridge, Carquinez Bridge, San Francisco-Oakland Bay Bridge, a proposed Richmond-San Rafael Bridge, Antioch Bridge, U.S. Engineer Foundation's Committee on Arch Dam Investigation, Spring Valley Water Company, and others. Also includes materials on masonry structures (chiefly dams), the Hetch Hetchy Project, Lake Spaulding Dam, and other bridges and dams in California and elsewhere.