This report is based on a study of the water and related land resources in the Potomac River basin and presents that part of the comprehensive plan for the prevention or control of floods and the development and conservation of the water and related land resources with respect to present and future needs in the upstream portions of the basin. The survey and investigations covered present rural land and water use and management in relation to the major water resource problems in the basin. They also considered past use and management as a basis for establishing trends leading to projections of necessary development programs from now to 2010. Determination of overall water needs and an analysis of possible means of development and control for a comprehensive plan required a joint appraisal by contributing agencies. It included expected future municipal, industrial, agricultural, and recreational developments and water needs in the basin. The Department of Agriculture developed information on: (1) trends in agricultural development and their relation to present and future water needs for agriculture; (2) erosion as it relates to the sediment and pollution problems; (3) local needs for water control and management in the upstream areas; and (4) the potential of upstream development for meeting these problems.