As proprietor or guardian of the vast area of public lands in the western part of the United States, Congress has made appropriation of the funds resulting from the disposal of portions of these lands to be used in the storage and distribution of water occurring in the arid and semi-arid States and under the terms of the Newlands or Reclamation Act, 17 June 1902, has provided for the irrigation of extensive tracts, the Reclamation Service being created for this purpose. It has expended over $100, 000,000 in building large works such as the Roosevelt Dam in Arizona, the Arrowrock Dam, 350 feet high, the highest in the world, in Idaho, and other great structures, including tunnels, canals and subsidiary works, such as roads, railroads, electric transmission lines and minor manufacturing plants, all for the purpose directly or indirectly of conserving and utilizing the natural resources of the country.
The science of hydro-economics may thus be said to bring together for practical applica tion many of the subjects which form portions of physics, chemistry, meteorology, hydrology, hydrography and hydraulics and to combine these in the building of waterworks, sewers and disposal works for towns and cities. Also
for irrigation and drainage systems, for power plants — electrical or otherwise, — for steam production, for flood prevention, by forest growth, reservoirs or other means, also for flood protection by levees or dikes, and finally for navigation including the character and size of channels and related details, boats, barges and terminal facilities. The constitutional and legal phases introduced by Federal, State or mu nicipal laws and the interpretation by the courts of the common law regarding riparian rights as well as statutory enactment have a part.
Bibliography.— Inland Waterways Com mission, Preliminary Report, 1908; Interna tional Engineering Congress, 1915; Transac tions — Waterways and Irrigation, 1916; Mead, Daniel W., (Hydrology— the Fundamental Basis of Hydraulic Engineering) (1917, pri vately printed) ; Meyer, Adolph P., The Ele ments of Hydrology) (1917) ; National Con servation Commission, various reports; Newell, F. H., The Public Lands .and their Water Supply,) also ; Pittsburgh Flood Commission, Report, 1911; Van Hise, Charles R., of the National Resources of the United States.)