This report has been prepared as a contribution to the development of southeastern Bucks County, Pa. It summarizes available information on the water resources of this 90-square mile area and evaluates current supplies. Future development of the area may change both the available quantity and the quality of the water supply. The effective development of the area demands a continuing knowledge of the water used and the potential quantity and quality of water available from both underground and surface sources. The area is strategically important to a great industrial section of the Bast. Its eastern boundary is a 26-mile segment of the Delaware River along the extreme southeastern border of Bucks County, Pa. (fig. 1). The present.population of the area is about 40,000, including 24,800 in Bristol Borough and Township and 6,770 in Morrisville. The area is traversed by both the Pennsylvania and the Reading Railroads and also by U.S. Highways 1 and 13. These are main transportation routes connecting the great market outlets of Philadelphia and New York. The Delaware River'is navigable from Morrisville to the sea. The area is only a short distance upstream from the Port of Philadelphia, which ranks second only to New York as the most important seaport in the United States. The area is mostly flat, open land 10 to 60 feet above mean sea level. It contains several large Industries, concentrated chiefly in the Bristol area (pi. 1). There are also scattered industries in the Morrisville, Langhorne, and Bensalem areas. However, Bucks County retains some of the characteristics of a farming region. Truck farming and gardening are still carried on to a considerable extent. Along Delaware River below Morrisville the mining of sand and gravel is an Important industry. The facts summarized in this report have been accumulated over a period of 25 years or more by Federal, State, and local agencies in connection with Investigations for other purposes. Most of the data used in this report have been obtained by the United States Geological Survey in cooperation with the Pennsylvania Department of Forests and Waters, the Pennsylvania Department of Internal Affairs, the Pennsylvania Department of Commerce, and State Planning Board, the City of Philadelphia, the Corps of Engineers, and the Interstate Commission on the Delaware River Basin. This report was prepared in the Water Resources Division of the U.S.Geological Survey by Jack B. Qraham, District Geologist; John W. Mangan, District Engineer; and Walter F. White, Jr., District Chemist, under the general direction of C. G. Paulsen, Chief Hydraulic Engineer.