"July 1991 1003437 01." In upper and lower right margins: Louisiana. "Source: U.S. Geological Survey Hydrologic Unit map, 1974 and S.C.S. State Watershed Planning Staff." Indexed for watersheds. Available also through the Library of Congress Web site as a raster image.
United States. Soil Conservation Service; National Cartographic Center (U.S.)
1991
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