illegal to block the migration of fish, for example the white sturgeon in North America, so fish ladders must be provided by dam builders. See also Archimedes' screw Hydroelectricity References Notes Robert Sackett, Preservationist, PRSHPO (Original 1990 draft). Arleen Pabon, Certifying Official and State Historic Preservation Officer, State Historic Preservation Office, San Juan, Puerto Rico. September 9, 1994. In National Register of Historic Places Registration Form—Hacienda Buena Vista. United States Department of the Interior. National Park Service. (Washington, D.C.) Sources External links Introductory turbine math European Union publication, Layman's hydropower handbook,12 MB pdf "Selecting Hydraulic Reaction Turbines", US Bureau of Reclamation publication, 48 MB pdf "Laboratory for hydraulic machines", Lausanne (Switzerland) DoradoVista, Small Hydro Power Information Articles containing video clips