Cities in the West are booming. But will they actually need a lot more water?
Previous studies showed the trend clearly for some large utilities. As a megadrought has baked the Southwest since 2000 , the region's biggest cities have reined in their use to keep pace with the declining supply.
But it had been years since someone took a more region-wide look at who was conserving and how much. Richter, a lecturer at the University of Virginia, and president of his own independent research firm, Sustainable Waters, was up to the task.
After gathering data for 28 large and medium-size water utilities dependent on the Colorado River, Richter and his team were able to see the more modern trend lines in sharp detail. The results surprised him. It wasn't just that cities like Denver, Los Angeles, Tucson and Las Vegas were using less. They were doing it while growing rapidly.
His 2023 study found that collectively the region's cities had grown by 25% from 2000 to 2020, while their water use dropped by 18%. Per person use rates declined even more sharply, falling by 30%.
"We thought that was nothing short of miraculous, to be honest," Richter said. "It's quite a water conservation success story."
Richter had heard the region's growth anxieties before. As homes spring up, highways widen and new schools open, conversations about rising populations in the arid West eventually find their way to water. Those new residents mean more green lawns and household faucets, forcing cities to scramble to meet the new demand, or so the thinking goes.
It's easy to understand why the notion that more people beget more water use jumps to people's minds, Richter said. All of the on-the-ground impacts of growth are highly visible.
"What you can't see so easily are the numbers, the water numbers behind that growth," Richter said. "We felt it was really important to start getting those numbers out there, and to start revealing the fact that it's not necessarily true any longer, that as a city's population grows its water use has to increase at the same time."
Now, as pressure from climate change mounts, the region faces a critical question: Can urban areas keep pace with their past successes in water conservation, or is there a floor to just how much water savings can be wrung from Southwestern cities?
Using less in Colorado SpringsUntil 2002, Colorado Springs was using water like there's no tomorrow. As the city grew, so did its water demand, hand-in-hand.
"There was a lot of inefficiency out there, a lot of inefficient fixtures, a lot of landscape irrigation, primarily of turf grass," said Scott Winter, Colorado Springs Utilities water conservation project manager. "A lot of it was, frankly, egregious."
A punishing drought in 2002 provided a shock to the system. While reservoirs declined, the people in charge of Colorado Springs started to realize that unchecked water use would eventually lead to serious shortages. Mandatory restrictions on use at the city level ran from 2002 to 2005.
"I don't think people thought of the water system, the water supply, as being constrained in any way until we hit 2002 and then our perspective changed on the scarcity of water and how reliable our supply was," Winter said.
Conservation is now seen as a reliable way to live within their means, he said.
Colorado Springs has taken a gradual approach. First came the rate changes. Residents who irrigated more paid more per gallon. Then came the incentives to swap out indoor plumbing fixtures, such as replacing a toilet that uses 5 gallons per flush with a new model that uses less than 1.
The city has also begun to embrace the loss of its lawns. It ramped up its lawn replacement program, in which thirsty yards are replaced with native grasses, like blue grama or buffalo grass, which use 60%-80% less water. The utility offers 50 cents per square foot of lawn converted.
Since Colorado Springs started those conversions in 2013, the city has swapped in native grass on about 3.1 million square feet, or about 72 acres, mostly on commercial properties like shopping centers, churches and business parks. In 2020 a permanent shift to only allow for three days per week of outside watering on existing grass went into effect as well.
All of the focus on conservation is paying off, Winter said. From 2000 to 2023, Colorado Springs has grown by about 40%, while also recording a 39% reduction in average per capita water use and about a 25% drop in total water deliveries. The city's water use is now about equal to what it was in the late 1980s, despite the rapid growth, he said.
Mandatory conservation measures have started taking hold in some parts of the Colorado River Basin, like a nonfunctional turf ban in Las Vegas, for example. But Winter said the cultural and political contours of Colorado Springs mean water managers have to get creative, relying more on voluntary incentives than strict mandates that could rile its conservative voter base.
When the city decided to overhaul its building code a few years ago, the process brought up the usual tensions over growth. One code change ruffled feathers. A restriction on new developments limited turf to 25% of the total landscape.
"Individual freedom is a core value here," said Nancy Henjum, a Colorado Springs city council member. Henjum summarized the early complaints of some fellow council members: "What do you mean I wouldn't be able to have Kentucky bluegrass in my whole yard?"
But after lengthy discussions, plus field trips to the infrastructure that brings Colorado River basin water over the mountains to Colorado Springs, lightbulbs went off for the city council members about the scarce nature of their supply, she said. As of June 2023, the turf restriction is now officially part of the city's landscape code.
"It was ultimately fascinating to watch people who are policymakers kind of push back initially, and then little by little over time recognize this is the right thing to do," Henjum said.
Conserving the way outWhile city leaders are proud of the water conservation success they've had over the past two decades, they say that was the easy part. In Colorado Springs, another 40% reduction in use over the next few decades will be tough, if not impossible, Winter said.
"Used to be that we could put a conservation program out there and anyone could participate. Almost everyone was inefficient, and so you could just broadcast a program out there and it worked," he said. "It's getting harder, it's getting more expensive. We're having to get a lot more strategic and targeted in our approach."
The same is true just to the north, in Aurora. The city grew by 40% from 2000 to 2020, while lowering both its total water use and per-person use, according to Richter's study.
"We are the first city (in Colorado) to pass a turf ban ," said Alex Davis, assistant general manager for Aurora Water. "Fifty percent of our use is outdoor water use in the summer, and we're trying to ratchet that down."
But Davis isn't convinced a city like Aurora, with its steep population curve, can rely solely on conservation to make its way toward a stable water future.
"When we look at our demand projections going forward, we have a gap that we need to fill, right?" she said. "We have a projected need that we can't meet today for what we expect the population to be in 2060, and so we have to acquire more water resources and do more supply projects in order to meet that gap."
A big portion of that gap is being driven by climate change, Davis said. Longer, hotter dry spells mean the uncertainty about future water supplies is greater than it was 20 years ago. Her team uses models to game out what kinds of policies the city might need to make it through extreme droughts.
Under those severe scenarios, Aurora's plans indicate it would first cut down on outdoor watering , then eliminate it all together. That would leave just indoor, household use, but Davis said, "there are projections where we don't have enough water to meet household use only in these very severe projected scenarios."
John Fleck, a University of New Mexico water policy professor, said this is the challenging future facing many of the West's municipal water leaders. Even so, he cautioned against too much hand-wringing over population growth and urban water use. There's still a lot of slack in the system and a lot more savings to be had, he said.
Because so much water is used outdoors, Western cities face a fundamental question: As the region warms and dries, how much green space are they willing to part with to close the gap between supply and demand? It'll be a tough call, but not an impossible one, Fleck said.
"When you think deeply about it, it would be weird for people, for communities, not to take the necessary steps to ensure their future existence, right?" he said.
"If you're facing the choice of getting rid of some swimming pools and lawns, or abandoning your city, it's a no-brainer. People are going to use less water. And that's what we see happen over and over again."
How you can save water at homeIn 2016, the Environmental Protection Agency said in-home water use breaks down like this:
, Denver Water
