Water management policies to reduce the overallocation of water

The Rio Grande/Bravo basin (Figure 1.a) has a severe problem of over allocation of water rights (Wong et all 2007), especially in the Rio Conchos (Figure 1.b) tributary of Mexico; due to a misunderstanding of the basin’s hydrology and incorrect water rights allocations policies in the 1970’s and 80’s (Aboites 2002). Historically, the hydrology of the basin has shown periods of 25 years with plenty of water followed by extended drought periods of 10 years. During the decades of the 1970’s and 80’s, a wet period, there was an increase in the allocation of water rights in the basin, mostly in the irrigation districts. Later, from 1992 to 2002, an extended drought period occurred, threatening not only the water users but also the international obligations of water delivery in the Treaty of 1944 between Mexico and the U.S. In fact, during the drought period of 1992 to 2002, there was a deficit of water delivery for the treaty obligations from Mexico to the U.S. In 2005, the International Water and Boundary Commission (IBWC), which is the international water committee responsible to ensure the 1944 treaty compliance, reported the deficit of water was completely paid (IBWC-CILA 2005). At this point, the IBWC, the National Water Commission of Mexico (CONAGUA) and the Texas Commission on Environmental Quality (TCEQ), the last two institutions are the federal and state agency in charge of the water rights and water allocation in Mexico and Texas respectively, realized the over allocation of water and the necessity to solve this problem before another drought period comes. Nowadays, there is not enough water in the basin to meet the institutional and international obligations that the Rio Grande/Bravo basin is subject to. Due to the lack of water availability for certain irrigation districts in Mexico, such as irrigation district 00