lf you have any questions about water shortages coming to a region near you, it’s time to take another look. Predictions based on global climate change have authorities warning that as many as 36 states will face significant water shortages in the decades ahead. The problem is especially acute in the West, where many communities depend precariously on winter snow packs for summer water supplies. But it also exists in the Southeast and other regions where infrastructure investment has lagged behind population growth. Even traditionally water-rich regions like Portland, Ore., and Atlanta have experienced drought emergencies during the past 20 years. A statewide drought in 2009 affected all of California, leading to water restrictions in every major city there.
What’s different about water shortages, compared to energy shortages? First, there are no new water supply sources to speak of, compared with potentially abundant alternative energy supplies such as solar and wind. In the case of water, all we can see are reductions in available supplies, as global warming is expected to make a good part of North America warmer and drier over the next few decades. Most of the available surface supplies in the U.S. are fully allocated, even as we are set to add another 100 million people by 2050. Second, much of water use is constrained by law and regulation, so that even available supplies can’t be sold or transported from water-rich regions to water-poor areas. While there is a global commodity market for oil, coal, and natural gas, water must be generally found and consumed where nature sees fit to deliver it. The good news? We’re still so water wasteful, there’s plenty of room for conservation to stretch supplies, and we’re technologically advanced enough to find ways to get a second and third use out of each drop, through on-site and off-site water treatment and reuse systems.
For example, average water use in the U.S. is about 150 gallons per capita per day (gpcd), ranging from 100 gpcd in the thrifty and water-rich Northeast to 300 gpcd in the arid (and not so thrifty) reaches of Las Vegas. By contrast, an even drier country, Australia, has been able to reduce per capita consumption to 155 liters (41 gallons) per day, 70% less, without sacrificing amenities that we consider valuable for our contemporary lifestyles.
Water and the Environment
We tend of think of everything in nature as available for human use; however, nature has a lot of other uses for water, and we ignore them at our peril. Without changes in our usage patterns, agriculture, industry, and cities will within a decade or two be using almost all of the freshwater nature supplies. In my home state of Arizona, predictions are that freshwater withdrawals could tap as much as 85% of all annual stream flows by 2030.
When I was a kid, if you took too much water from the drinking fountain, the other kids would say, “Leave some for the fishes!” That was fanciful, but metaphorically accurate. We do need to leave some for the fish. As it is, almost all of the water in two major river basins, the Colorado and the Rio Grande, is gone long before the river reaches the ocean because of upstream withdrawals for humans. In California, much of the water supply from federal dams originally destined to go from the wet northern part of the state to the dry southern part is constrained by federal judges to remain in the Sacramento-San Joaquin Delta for fish habitat. So even where there is water, it’s not all available to us. Nature wants her share and, as the saying goes, “Nature bats last!”