Increasing Lakes Powell and Mead's Available Storage by Accounting for Evaporation Losses

This study seeks to promote sustainable management of the two largest reservoirs in the Colorado River basin, Lakes Powell and Mead, by accounting for evaporation losses in Lower Basin deliveries. Although evaporation losses are currently ~7% of the total basin demands, they are currently unaccounted for in basin deliveries. This project assigns evaporation loss responsibility to water users when Mead’s pool elevation is ≤ 1090 ft by proportionally decreasing their allotment based on yearly evaporation totals and the user’s current delivery schedule. To achieve this, a new delivery rule is created in the Colorado River Simulation System (CRSS), as modeled in RiverWare. To determine the efficacy of evaporation loss inclusion as a solution to declining reservoir levels, a performance metric is defined, and reservoir elevation levels are compared between CRSS simulations with and without evaporation loss inclusion.