Water security in the Las Vegas Valley has been a question mark for a long time. Lake Mead and the Colorado River commonly make headlines for increasingly dire drought conditions, interstate tug-of-wars on water allocations, and lawsuits aimed at sorting it all out. 

Through a combination of ordinances, regulations, and recycling, Southern Nevada has repositioned itself into a global model for water efficiency. But there’s more to be done for a region that gets nearly all of its water from a single (diminishing) source.

“We’ve done an admirable job of trying to conserve our way out of the water situation we are in, but we’ve been in an extended drought for over 25 years,” said Dale Devitt, UNLV life sciences professor and director of the university’s Center for Urban Water Conservation. “It’s a real challenge to have 2.3 million people living in such an arid environment solely dependent on 90% of its water from the Colorado River.”

Devitt’s been researching and working on community-focused water conservation projects for more than three decades. He founded the center in the mid-1990s and holds a joint appointment with University of Nevada, Reno Extension. He’s also authored dozens of research publications and in 2020 co-authored a book on the selection and maintenance of trees in urban desert landscapes. 

To learn more about the center’s ongoing efforts to conserve water and maximize our use of it, check out this story’s companion piece “Using Water Wisely and Making it Count”. 

But for now, Devitt’s going to give us his take on the sustainability of Lake Mead, backyard water conservation, watering tips, and how to listen to what your plants are telling you.

Let’s start with a big one: What does the future of Lake Mead look like?

I think our ability to predict the future is not as good as we’d hoped it would be, especially as it relates to climate change. As we collect data, we realize that we’re in this continued warming trend, so we need to stay vigilant and prepare for a worst-case scenario so we’re not caught off guard. 

There’s much we can do to save water and pursue other sources of water, such as desalinated ocean water. We’re going to have to be creative, to say the least, if we’re to maintain population growth. We need to find better ways to transfer water from one region to the next without undermining the hydrologic and ecologic systems that also depend on it. 

Nevada is very fortunate because we get what’s called return-flow credits. We take water from the Colorado River, use it, and then that water which goes through the waste process is treated and returned to Lake Mead. We can transfer that treated reuse water back “one for one” for Colorado River water.

About 200,000 acre feet come back as return-flow credit. It really gets down to economics, and it’s all about power in terms of electricity to run pumps. If water runs uphill, it’s more expensive. The Southern Nevada Water Authority developed zones of conservation where the waste water is treated and discharged to local golf courses and parks, which has been very effective.

We need to use treated, reuse water wherever it makes sense. We don’t want to get ourselves to where the well runs dry before we make adjustments to how we’re using water. A lot can be done as far as conserving water. But we need to look at long-term sustainability. Do we have enough water resources to support continued growth? 

Since I moved here in 1984, the population has been on a steep growth curve. We needed to think about how we were using water even back then. We’re going to have to really look to see if there are other sources of water that can be accessed at a reasonable cost. 

Do resource-intensive AI data centers have a place in the parched Southwest?

Every community has the right to use its water in a way that benefits it. And that means supporting economic growth. We need to consider that when we decide whether it makes sense to support data centers if they’re using significant amounts of water. We definitely need to avoid evaporative cooling of data centers, as a large data center using this method may use as much as one to five million gallons of water per day at peak demand. 

How much water does grass use? 

There’s a difference between cool season grasses like tall fescue, and warm season grasses like bermuda grass. A lot of people merge them together as if turf grass is one entity when it’s not. Tall fescue uses 30% more water than bermuda grass. The Urban Water Conservation Center is really putting emphasis on the replacement of cool season grasses with warm season grasses, but we also need to continue strongly promoting desert-friendly landscaping.

How much watering do desert backyards really need?

We need to get people on the bell-shaped curve of environmental demand. The demand for water by plants is very low in the winter, steps up in the spring, peaks in the summer, steps back down in the fall, and returns back to baseline in the winter. If we can get people on the bell-shaped curve, we can start to fine tune it and really help them save water. If they aren’t, it will be more challenging to get them synchronized with what the true water requirements are.

And while irrigating the right amount is a challenge, for sure, I think part of it is selecting the right plants. This includes desert-native plants and desert-adapted plants. There’s really no place for cool season turf grass. We want to focus on the warm season grasses, native shrubs, native trees, and drip irrigation.

What is a yellowing plant in our backyard or patio trying to tell us?

Never avoid trying to interpret what plants are telling you because they often have telltale signs when they’re under stress. When the leaves start to lose color and turn pale, those are called chlorotic leaves and oftentimes associated with low iron (newer leaves) and/or low nitrogen (older leaves). But if leaves are curling, browning at the tips and drooping, these are signs that the plant is receiving inadequate amounts of water.  

Native shrubs use as much as 70% of their carbon allocation to develop root systems. And these root systems are extensive, and compete for that little bit of rainfall. Many shrubs and trees will develop roots under turfgrass. If the turfgrass is removed and the irrigation system isn’t modified, the trees and shrubs will be placed under greater stress. 

Every backyard is different in terms of size and plant composition. Because of that, we all have to pay better attention to their needs, and if those needs are suitable for a desert climate. We each really need to try being a bit of a scientist with our backyards.

What’s the most ambitious project coming up?

We have a collaboration between UNLV and UNR Extension that really reaches out beyond the Center for Urban Water Conservation called NevMet, or Nevada Meteorological.

It’s linked by five weather stations – one at the center, and the other four are on golf courses throughout the valley. These stations will download data to a website where users can select which station is closest to them, and download unique weather data including the assessment of environmental demand – which is the aforementioned bell-shaped curve. 

There will be a library of information that fully instructs users on how to interpret and use the realtime data to their benefit. The hope is that this will allow homeowners, businessowners, and anyone else to more accurately schedule their irrigations. We’re excited to launch that more fully in the next few months.

A lot of emphasis is placed on water use in the urban landscape. There's a lot of water that can be saved there, but we want to do it in a way that makes sense, allows the plants to grow and be healthy. We've done a lot to quantify the water use of turf grass, shrubs, and trees. We have those numbers, which will be available with the launch of NevMet.