Lake Mead is the largest reservoir in the country. It’s located on the Colorado River, which provides water for about 27 million people in seven states, including millions of Californians. In fact, California gets more than a trillion gallons of water from the Colorado River each year, directly from Lake Mead via the Colorado River Aqueduct which snakes across the desert. Eighteen million people in Southern California are dependent on the Colorado for 40% of their water. And for some agricultural operations, that percentage is more like 100. Needless to say, it’s a critical source of water.
The thing is, after 11 years of dry conditions in the region, Lake Mead dropped to its lowest level ever in October. And so far, it’s stayed there. Since Hoover Dam was completed in the 1937 the water level has never been so low. As of today, it’s at 38% of capacity. And it’s not just Lake Mead that’s low. The whole Colorado River storage system is at just 55% of capacity, so forget just filling it up with water from upstream. Of course, winter’s on it’s way, and with that, precipitation, so the lake shouldn’t stay quite so low for long. And, thanks to a wet year, Northern California’s reservoirs are doing well.
But when you think about this water shortage in terms of population trends and the changing climate, the future for water in the Southwest looks grim. Population areas supplied by the Colorado River are some of the fastest growing in the country. So demand is going up. At the same time, scientists and water managers say the supply will go down. The region is expected to get warmer and drier in the coming decades, which means less precipitation, and more specifically, less snow. Which means that of the precipitation that does come, more will come as rain, which is harder to capture and store for use throughout the dry summer months.
In fact, studies show that the river’s flow is likely to decrease 10-15% in coming decades due to climate change, according to the Bureau of Reclamation’s Terry Fulp, and, he said, the demand is already outpacing the supply.
“The supply and demand curves have crossed,” he told me last May.
The question of just how long the Colorado River can continue meet the needs of seven states with growing populations, depends on how quickly those supply and demand curves are diverging. Scientists have given varying estimates of when Lake Mead will go dry, but recent studies estimate a 50-50 chance that it could happen before 2057. (Earlier studies had estimated it as soon as 2021.) The state’s population is expected to increase by half, to nearly 60 million, by 2050.
So, Californians, what happens then? And what should we be doing now to prepare? It might be worth thinking about. In 2060, taking shorter showers and turning off the water when you brush your teeth might not be enough.