Linear quadratic control models were utilized to analyze problems of conjunctive use of surface and groundwater in two California settings: (1) Yolo County, where a finite element hydrologic model was developed to provide physical data for an economic model, and (2) Kern County where groundwater overdrafting has been a long standing issue.

The principal [sic] thrust of the Yolo study was to determine the economic efficiency of spatial surface and groundwater allocations and the efficiency of intertemporal groundwater decisions, given the common property problems arising from uncontrolled groundwater use.

The Kern study had two primary threats: (1) to model groundwater demands and supplies and determine the optimal steady state depths of water tables in various areas and the factors influencing the optimal steady state, and (2) to model water quality linkages with quantity in order to derive implications for efficient water allocation, management, and control.

Study results show clear evidence of significant resource misallocation of water both spatially and temporally. Severe impediments to efficient water mobility exist in legal and administrative allocation processes. Some control over groundwater use is shown to be needed and some state policy governing groundwater use is recommended. Implementation is required, however, only in a limited number of critical groundwater basins in the near future.