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Water scarcity is a worldwide issue. March 22nd has been declared by UN-Water& FAO, as the world water day. The 2007 world water day theme was “Coping with water scarcity”. Water scarcity is defined as the point at which the aggregate impact of all users impinges on the supply or quality of water under prevailing institutional arrangements to the extent that the demand by all sectors, including the environment, cannot be satisfied fully” (UN-Water & FAO, 2007, p.). Although scarcity could be a social construct or the consequence of changing patterns in water supply, there are many options of being remedied or alleviated. Traditionally, it has been addressed through supply or engineering oriented solutions more than enforcing conservation options. Supply oriented approach assumes that water scarcity problems only exist when there was not enough water to meet social and productive demands. Increasing water supply infrastructure solves the water shortage problems. Under this approach, the main problem is how to identify a need and then how to make water available. As a consequence, dams, reservoirs and facilities for meeting these increasing human needs have been built, and rivers and streams diverted. Currently, 45 000 big dams, plus another 800 000 smaller ones have been built (MEA, 2005). Although this infrastructure building has brought about positive effects, negative effects have also been perceived. For humans, positive effects have been in terms of stabilizing flows for use in irrigated agriculture, flood control, drinking water supply and hydroelectricity production. Negatives effects are given in relation to capital costs per cubic meter of new supply are doubling every decade, environmental effects are more severe, and adverse effects on indigenous peoples are no longer acceptable (MEA, 2005). As a consequence of these effects, the water supply model was restructured in the Johannesburg World Summit on Sustainable Development in 2002. In fact, the failure of this model was recognized by the World Bank long time ago, during the Ninth Irrigation and Drainage Conference in 1992. Since this conference, it was recommended the need to change this approach. Two key constraints of this approach were pointed out, namely the increasing scarcity of water and the higher costs of projects both in technical and environmental terms. Furthermore, it was also recognized that a focus on the technical supply issues and less on how water was used and disposed of, left open the expectations that additional quantities of water supply could always relieve scarcity (Easter, et al. 1992). Although in Mexico, this approach has been reviewed as a consequence of the increasing costs necessary to exploit new water sources, in practice it still

Planning Approaches to the Management of Water Problems in Mexico