Lake Powell and Lake Mead are currently operated under an "equalization" policy that governs releases from Glen Canyon Dam. In order to maintain hydropower generation at both Glen Canyon and Hoover Dams, the lakes must be kept at approximately the same level. However, by spreading out the water, evaporation is greatly increased. Since the year 2000, Lake Mead has steadily declined toward the critical level at which a shortage would be declared for the Lower Basin states. A plan called "Fill Mead First", which would drain Lake Powell in order to refill Lake Mead, has gained traction in recent years. Glen Canyon Dam would remain in place (as total removal of the structure would be prohibitively expensive), but would only store water in wet seasons when runoff exceeds the capacity of Lake Mead to hold it.