The Federal Water Pollution Control Act (Section 16 (a)) directs the Secretary of the Interior to conduct a comprehensive analysis of the national requirements for, and the cost of, treating municipal, industrial, and other wastewater effluents to attain water quality standards established under the Act. This first analysis is required to be submitted to the Congress by January 10, 1968, to cover Fiscal Years 1969-1973, inclusive, and to be updated each year thereafter. This is Volume IV of the report (State and Major River Basin Municipal Tables) containing a tabular breakdown of estimated construction costs of municipal treatment works and sanitary sewers, and the operation and maintenance costs of treatment works. The data are shown for each of the 50 states and District of Columbia and the Nation's major river basins as described by the Water Resources Council.