Reston, Va. : Geological Survey,
maps : col. ; 238 x 253 cm. or smaller, on sheets 169 x 168 cm. or smaller.
Shows the hydrologic units that supplanted the units previously used by the U.S. Geological Survey in its Catalog of information on water data (1966-72). Shows the regional, subregional, and accounting unit boundaries of each state together with the corresponding eight-letter hydrologic unit codes./
Relief shown by spot heights. Depths shown by isolines./
Some sheets prepared in cooperation with the U.S. Water Resources Council./
Alaska sheet prepared in cooperation with the Interagency Hydrology Committee for Alaska./ Predominant scale: 1:500,000. Alaska sheet is at 1:2,500,000./
Caribbean region sheet includes ancillary maps: Puerto Rico (1:240,000) -- Virgin Islands (1:1,000,000) -- Canal Zone (1:1,000,000) -- Serrana Bank and Roncador Bank (1:1,000,000) -- Navassa Island (1:250,000).