ABSTRACT
The doctrine of prior appropriation is the prevailing water law doctrine for surface waters nearly everywhere in the West. The requirement that a water right depends on the beneficial use of the quantity allocated under that right reduces the incentives of water right holders to conserve water. The application of diverse and conflicting doctrines to surface and groundwater obviously flies in the face of hydrologic reality in settings where surface and groundwater are clearly interconnected. Efficiency in irrigation depends on the acceptance by farmers of measures that reduce the quantity of water applied while maintaining or enhancing the return on their investment. Laws and regulations to improve the quality of the environment may constrain or provide incentives for conservation of water, depending on the site one is dealing with. The district or mutual water company is the overall manager of the district's water supply, which may include water from several sources: surface water rights, stored water rights, and groundwater.
