Few convictions are more generally or more firmly fixed in the minds of the people of California than that our number one economic problem is to put to best use our invaluable water supply. Previous investigations have shown that this supply is adequate for a population much larger than the present 10,500,000, and that with additional storage and redistribution of water, most of the agricultural lands of the State, except only some desert and higher areas, can be serviced for irrigation as our expanding economy and human requirements justify the costs involved. Furthermore, without too great a sacrifice of reasonable needs, our multiple uses of water for domestic and municipal consumption, for agriculture, industry, power, recreation, and wild life preservation can be so coordinated as to achieve maximum benefits for the largest number of people.

This bulletin presents the first results of new studies, under direction of the State Water Resources Board, aimed at a solution of this number one problem. It brings together in one volume the principal basic data regarding water in California that have been accumulated up to 1947, thereby becoming an inventory of the water resources of the State. Concurrently with preparafion of this inventory, work has progressed on the other principal phases of the program: determination of present use of water and of ultimate water requirement, and formulation of "The California yvater Plan" to meet that requirement.