dr. maddock: the real problem that we have is that with increasing populations and shortages of water, we are becoming very vulnerable. in the southwest, there's a very unique vulnerability here, simply because where do we get the water if there is no water? narrator: across the country in northern florida, the quantity of water isn't an issue. rainfall averages an abundant 1 1/4 meters each year. wendy graham and her colleagues evaluate and model the impacts of industrial and agricultural land use threatening the world's largest collection of freshwater springs. dr. graham: right now, the biggest question is how far we can stress the system and not push it past the point of no return. narrator: both researchers are working towards a sustainable future to protect the water needed by our species and our planet. arizona is one of the fastest-growing states in the u.s. the consequent demand on freshwater for personal, industrial, and agricultural use is depleting the natural resource and des