Technical Abstract: Groundwater extraction from the Calera Aquifer in the State of Zacatecas, Mexico, for irrigation, urban, and industrial uses has increased over recent decades to unsustainable levels. By 2015, irrigated agriculture was projected to use about 84% of total extracted groundwater, urban 10%, and industry 6%. The annual groundwater deficit was estimated to be 172.5 [106 m3/yr] and groundwater table elevation to drop by 1.15 [m] per year. An annual, watershed-scale water budget analysis was conducted to evaluate alternative water management and conservation scenarios and determine their effectiveness at slowing the rate of groundwater depletion. The most restrictive scenario called for a 10% reduction in industrial and urban water use and a 50% reduction in irrigation water in the first decade after year 2015, and an additional 10% reduction in irrigation water every decade after year 2025. According to this latter scenario, annual groundwater deficit would drop to 45.5 [106 m3/yr] by year 2045, groundwater table would be 18.1 [m] lower than that in year 2015, and groundwater table elevation would drop 0.3 [m] per year. The 50% reduction in irrigation water was achieved by upgrading inefficient furrow irrigation to sprinkler and drip irrigation; converting under-performing crops (oats, corn, maize) to rain fed cropland; switching 30% of the dry bean crop to canola, a more water efficient crop; and, taking 15% of onion, garlic, and red pepper crops out of irrigated production. Additional cropland will have to be taken out of irrigation to meet water use targets set for 2035 and 2045. This water management scenario would extend the useful life of the aquifer and represents a great improvement over current unsustainable groundwater extraction. However, curtailing irrigated agriculture beyond increasing irrigation efficiency may not be acceptable from a political and socio-economic stand point because it would impact the region’s agricultural economy.