"Economic Implications of Alternative Futures for Lake McConaughy"; Thomas Buell; Advisor: Raymond Suppalla. After four years of severe drawdown, 1999-2003, storage in Lake McConaughy was at a historic low of 20 percent and the amount of water in storage at the end of the irrigation season has remained close to that level ever since. This situation makes it very difficult to meet the combined needs of irrigation, hydropower and recreation. Prior analysis addressed the economic costs and benefits of augmenting storage to improve recreation by delaying releases from the reservoir for other purposes. The economic desirability of reducing releases to provide increased recreation benefits was found to depend on the probability of the reservoir filling to a spring level of 65 percent of capacity within three to five years. However, prior research did not address this probability, nor did it address the economics of augmenting inflows as an alternative to reduced releases. This study used a statistical hydrology approach to determine the reservoir refill probability distribution. A two stage ordinary least squares regression analysis found that nearly 90 percent of the variation in Lake McConaughy inflows can be explained by current year runoff (snowmelt), upstream storage and upstream irrigation development. The statistical results were used to simulate reservoir inflows and refill probabilities. Results suggest that there is a 70 percent chance that it will take more than five years for the reservoir to reach 65 percent of capacity, which is the ideal level for recreation. This statistical model was also used to estimate the economic effects on recreation, hydropower and irrigation of policies to augment inflows to the reservoir, or temporarily reduce releases. The model shows that if policy makers want to increase inflows to the reservoir by reducing upstream irrigation an allocation approach would be less costly than reducing irrigated acres. However, neither method of limiting upstream irrigation was found to be an economically cost efficient solution. Results suggest that reducing releases would produce a greater net economic benefit than increasing inflows, and would be economically efficient in some cases.