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368 assessment of climate change in the southwest united statesFigure 16.9 Rio Grande Basin.Source: Lacewell et al. (2010).The Rio Grande and its associated aquifers are the principal and often only watersource for cities and farms from southern Colorado through New Mexico and into farwest Texas (Hurd and Coonrod 2007). The vulnerability that these wa ter users face inlight of potential climatic and hydrologic changes is indicated not only by their dependenceon a sole source of supply but by the oversubscribed claims to and exhaustiveuse of this source (Hurd et al. 2006; Hurd and Coonrod 2007). Using a hydro-economicmodel developed for the Upper Rio Grande, Hurd and Coonrod (2007, 2008) identifiedthe following significant vulnerabilities for New Mexico based on a “middle severity”future climate change scenario:• A reduction in long-run average water supply leading to a 2% reduction by 2030and 18% by 2080, with the reduction affecting agriculture in 2030 and both agricultureand urban areas in 2080;• Increases in water prices, as demand exceeds supply due to population growthand projected climate change;• A concomitant shift in consumptive use by urban areas at the expense ofagriculture;