In 1943 the towns of Lewes and Rehoboth entered into cooperation with the U.S. Geological Survey in order to study salt-water encroachment in that area. Three observation wells were established, of which one, NI 3, had observations continued on the statewide program in 1952. Cooperation with the town was conducted in 1950. In December 1949 the State of Delaware, through the Agricultural Extension Service of the University of Delaware and the Highway Department, cooperated with the U.S. Geological Survey for the purpose of making of a reconnaissance study of ground water within the State. In the fall of 1950, under the cooperative agreement with the Agricultural Extension Service of the University of Delaware, 13 water-table wells were established for measurement. Beginning July 1, 1951, cooperation transferred to the Delaware Geological Survey of the University of Delaware, and measurement s continued the remainder of the year. Cooperation was also established with the Delaware Geological Survey representing the city of Newark for a detailed study of the Newark area. An additional observation well, Cb 123, was established in the course of this program.