The Colorado River is like a giant bank account for seven different states. Now it’s running short. For decades, the river has fed growing cities from Denver to Los Angeles. A lot of the produce in supermarkets across the country was grown with Colorado River water. But with climate change, and severe drought, the river is reaching a crisis point, and communities at each end of it are reacting very differently. Just outside Boulder, Colo., surrounded by an evergreen forest, is Gross Reservoir.