This report is Vol. 9 of a comprehensive survey of the water resources of the Delaware River Basin undertaken in the 1950's by the U.S. Army Corps of Engineers. Philadelphia District. Appendix P is an investigation of water use projections for domestic, municipal and industrial water needs plus a study of surface water deficiencies in the Lehigh, Upper Schuylkill, Trenton-Philadelphia, Wilmington and Northern New Jersey areas. Formation of plan development is reported in Appendix Q. Water control problems, economic development, dimensions of the flood problem, hydroelectric power markets and both basic and alternative measures to augment supplies of useable water are given. Appendix R focuses on cost estimates for flood control measures. Studies described in Appendix S show that it would be feasible from an engineering standpoint to construct, operate and maintain a salt water barrier across the Delaware River near New Castle, Del. to halt the intrusion of salt water and create a large fresh water lake which would provide a suitable source of water supply for Northern Delaware. (Author).