Abstract
The water content in a reservoir allowing neither spillage nor emptiness during its design life was investigated for the case where the annual inflows are distributed as independent gamma variables, and the annual outflows are equal to the sample meani After the exact distribution of the water content was obtained, the formulae for computing its moments were provided. The expected values of the maximum amount of water in surplus, the maximum amount of water in deficit, and the storage capacity of the reservoir were also derived.