Operational problems at Hyalite Reservoir, Montana were investigated in a one-year pilot study. Hyalite is a single-purpose (irrigation) reservoir which is normally filled from snow runoff in April, May and June, and normally depleted in July, August and September. Flooding on Hyalite Creek is not normally a serious problem. However, some flood control benefits could be realized by utilizing snow survey data obtained by the U.S. Soil Conservation Service. In years of high winter precipitation, spring filling should be delayed so as to insure storage availability at the time of runoff peak. Linear programming and dynamic programming procedures were presented to demonstrate the feasibility of optimizing reservoir releases over a four-season period. As applied to Hyalite Reservoir, the techniques are of limited use, because spring inflows are almost always adequate to completely fill the reservoir. The techniques will be valuable when applied to a larger basin such as the Musselshell, which is under further investigation.