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in the Mexican Treaty obligation, However, future increases in upper basin depletions will depend on the ability of Lake Powell to supplement upper basin outflow during drought periods, This drawing from storage is the foundation purpose for the construction of Glen Canyon Dam, The most serious impacts of emptying Lake Powell is that there would no longer be reservoir storage to support additional upper basin uses and that the lower basin would receive uncontrolled flow, If flows to the lower basin were to fall below 75 MAF/IO years, then upper basin use would have to be curtailed to meet the delivery requirement of the 1922 Colorado River Compact, f - The loss of existing benefits from Lake Powell itself are self evident: power generation, lake recreation, downstream trout fishery, and the extended and moderated white water Grand Canyon boating season, The entire ecosystem of the Grand Canyon would likely change with the loss of the current food base, and non-native predator fish from Lake Mead could be a major concern to native fish species in the Grand Canyon, g - Significant increases could occur in lower basin consumptive uses as the result of curtailed upper basin uses, perhaps as much as 2 MAF annually during surplus conditions (equal to the foregone additional upper basin development up to the upper basin yield), Lower basin shortages could be eliminated as an alternative to increased uses since future risks of shortages to lower basin uses are primarily due to increases in upper basin use, The risk of flood control releases from Lake Mead would rise dramatically, meaning extra deliveries and flood flows to Mexico, As a result of these higher flows along the Parker - Davis floodway, river channel maintenance costs in the lower basin could also rise, Since upper basin increases in consumptive use would end, projected increases in salinity impacts might also decline, decreasing the need for additional salinity control projects, h - In order to carry out the Brower proposal, additional legislation would be required to negate the constraints of the 1968 Colorado River Basin Project Act. Specifically, these constraints pennit annual releases of water from Glen Canyon Dam in quantities greater than 8,23 MAF only if(l) required for lower basin consumptive use, (2) to equalize storage with Lake Mead. or (3) to avoid anticipated spills, Much greater releases would have to be made to empty Lake Powell. I - With such a radical change in the "plumbing" of the Colorado River reservoir system. it is likely that the Colorado River Compact, the Upper Colorado River Basin Compact, and the Mexican Water Treaty would be renegotiated, The political tunnoil thus created would be difficult to overstate, 2