Phoenix's long battle to supply its growing population with enough water is discussed in an article part of USA Today's "Weathering the Change" series. Phoenix, the fifth-largest city in the U.S., joins other Southwest cities like Los Angeles, Las Vegas and San Diego that are preparing for dwindling water supplies due to climate change. Arizona state climatologist and Sustainability Scientist Nancy Selover says, "Water is our biggest issue. You can never have enough water." The most recent National Climate Assessment shows that Phoenix's drought has been "unusually severe." We've sustained ourselves for so long thanks to the Colorado, Salt, and Verde Rivers and underground water. However, increasing temperatures pose health risks, especially for the elderly, homeless, and underprivileged.