Large Southwestern cities are bracing for cuts to their water supplies after the federal government stepped in last week with a 10-year plan to save the reservoirs on the Colorado River from crashing. Of the seven states that draw water from the river, none is likely to feel the impact more than Arizona. “The Department of Interior’s plan forces Arizona, and Central Arizona in particular, to take so much of these cuts.” But water deliveries to the downstream states of Arizona, California and Nevada could fall by up to 40%. Gallego said Phoenix has a diverse water supply.