Evaluation of Water Conservation Measures Implemented in the Rio Grande/Bravo Basin

As part of a set of immediate and long-term actions taken in the drought of 1994–2003, on July 3^rd2003, the Mexican and the U.S. sections of the International Boundary and Water Commission (IBWC) signed Minute 309; an amendment to the treaty of 1944 that specifies a set of water conservations measures implemented in the Rio Conchos basin and the conveyance of saved water to the main stream of the Rio Grande/Bravo on December and January. These water conservation measures include the reduction of conveyance losses and the increase in application efficiency on the farms in the basin, therefore, a substantial fraction of these savings are in the form of reductions in groundwater recharge, and not in the reduction of physical losses of the system. In this paper, we evaluate performance of the policy proposed in Minute 309 for aquifers, reservoirs, water users and the environment. This evaluation is done in a basin model constructed in the Water Evaluation and Planning system (WEAP) software. Additionally, a scenario where the water savings are delivered in environmental patterns is also presented. The description and evaluation of Minute 309 are presented along with a comparison against the current water management policies and the environmental pattern water savings delivery scenario.