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The "with agreement" simulation examines the flows that would have occurred had the reservoir been operated according to the agreement. We find that the depletions of the "without agreement" simulation have been cut approximately in half; the flow at the mouth of the Laramie is reduced by 21 000 acre-ft/yr, on average, which would reduce average flow at Overton by 1. 5%. However, during the years 1957 and 1958, when downstream users were trying to recover from the drought, reservoir replenishment under the terms of the agreement would have caused a 4% decrease in flow at Overton. The agreement does more than simply moderate the effects of the reservoir; it provides legal guarantees of certain minimum flows. The minimum guaranteed flow varies with the pattern of inflows and the reservoir level, but in all cases will exceed 23 000 acre-ft/yr. These flows take priority even over water use at the power plant itself. Without the agreement, there is no such guar- antee. Furthermore, without the agreement there is nothing to prevent addi- tional diversions of storage water from Grayrocks Reservoir, which would even further reduce the flow delivered into the North Platte. In the simulation of the reservoir operation with the agreement, no account was taken of the Corn Creek Irrigation Project. The agreement stipulates that Corn Creek, if it is ever built, is entitled to 22 500 acre-ft/yr from the reservoir. This obligation is to be met by reducing the minimum flows deliv- ered into the North Platte. In that event, however, MBPP may meet this obliga- tion either by releasing additional flows from Grayrocks or by buying up water rights in Wyoming to be delivered into the North Platte. MBPP will probably decide to purchase additional water rights rather than increase its releases from Grayrocks because even without Corn Creek there may be times when opera- tion of the power plant will have to be curtailed due to lack of water. These additional releases mean that Corn Creek, when and if it is built, will have only a small impact on the minimum flows guaranteed in the agreement. In fact, again assuming a return flow of 7500 acre-ft/yr, Corn Creek will only reduce the deliveries into the North Platte by about 3750 acre-ft/yr. More- over, even this decrease is not certain. Corn Creek ~ay use the 10 000 acre-ft remaining in Wyoming's share of Glendo Reservoir. Use of this allotment at Corn Creek will return perhaps 2000 to 4000 acre-ft to the North Platte; use of this water for any other purpose mayor may not return flow to the North Platte. 50