The drought 1945-56 in California affected principally the southern part of the State, and was one of a series that has been recorded in the past century. Although the precipitation in any individual year is not predictable, the pattern of alternating wetter and drier periods is consistent enough that there is clearly a- need for storing the surpluses of wetter periods to provide adequate water supplies in dry years. This cyclic storage is a basic element in the California water plan. Wherever the storage increments in wet years provide adequate supplies throughout the periods of precipitation deficiency, the effect of drought upon mankind has been overcome, or at least minimized. However, whenever the deficiency is greater than has been experienced in past droughts, some downward revisions may be necessary in previous estimates of the firm supply available for man's use.