This report describes the research experience of a state-level water planning and development agency ove the period 1965-1972. The Texas Water Development Board, constitutional water planning and development agency for the State of Texas, in this period initiated and conducted a sustained program of research that has developed techniques useful in decision-making believed to be generally applicable to water planning problems elsewhere. In this report, the conditions dictating the constraints and opportunities of the Texas Water Plan are described, the sequential steps in the research program and its results are outlined, and proposed facilities of the Texas Water System, major physical works component of the Plan, are used as an example for research and development of new planning techniques.