Adapting to a Drier Future

Fall 2021

Adapting to a Drier Future


The Colorado River system provides water for hydropower, agriculture, wildlife habitats, and nearly 40 million people in Arizona, California, Colorado, Nevada, New Mexico, Utah, Wyoming, and Mexico. In August, drought conditions and low reservoir levels led the US Department of the Interior’s Bureau of Reclamation to make the first-ever shortage declaration for the Colorado River.

This declaration didn’t come as a surprise to professional engineers in charge of water utilities and resources management in affected cities and counties. For decades, these areas of the West have experienced aridification challenges, while seeing significant population growth. PEs are at the forefront of managing infrastructure and developing water-use strategies essential to meeting the needs of their communities.

Climate change has created conditions of extreme dryness in the West. The Colorado River has experienced its driest 20-year period (2000–2019) in more than 100 years of record keeping, according to a bureau report. The Colorado River’s Lake Powell and Lake Mead reservoirs were nearly full in 1999, which provided ample water to meet demand during this drought period. This summer, the total Colorado River storage system was recorded at 40% of capacity—down from 49% in August 2020.

What does this shortage declaration mean? A level-one shortage condition triggers a drought contingency plan, beginning in January 2022, that will lower annual water allocations for the lower basin states Arizona and Nevada, which draw from Lake Mead. In July, the bureau released 181,000-acre feet of water from a storage project into Lake Powell, under drought operations protocols.

A Fundamental Change

The Southern Nevada Water Authority and Las Vegas Valley Water District (SNWA/LVVWD) oversee water distribution services to 2.3 million people in Las Vegas and Clark County. The Colorado River’s Lake Mead reservoir provides 90% of Southern Nevada’s water supply while the remaining 10% is from local groundwater.

Knowing that these conditions were on the horizon, the SNWA/LVVWD developed a 50-year resource plan. “We put conservation plans in place because we knew a shortage declaration was imminent,” says Colby Pellegrino, P.E., the deputy general manager of resources. “The community has to conserve across all sectors in order for us to continue to be ahead of the drought.”

When Pellegrino joined the agency in 2003, she supported Colorado River modeling efforts to anticipate changes caused by climate change and reduced flows. With 20 years of drought conditions, she says, there was no question that proactive steps were necessary. “The climate science says that it’s aridification. The West is undergoing a fundamental change, a permanent drying.”

Planning for flooding or water supply shortages has traditionally been based on historical data. But forecasting conditions can no longer be accomplished simply by looking at past records, says Pellegrino. “There is still a large range of variability in what future climate change projections show. Staying ahead of that is a constant education and adaptation process.”

Through robust conservation planning, water use has dropped by 23% in Las Vegas and Clark County, says Pellegrino, despite a population growth of over 750,000 people. Nevada’s Colorado River water allocation is 300,000 acre-feet, but last year’s use was 255,000 acre-feet. Next year’s allocation will be reduced to 279,000 acre-feet, nearly 7 billion gallons (21,000 acre-feet) less water. This reduction amount is enough to serve about 45,000 households for a year, according to the SNWA/LVVWD.

In anticipation of the future decline of Lake Mead’s water level, the SNWA/LVVWD began a $1.4 billion project to construct a third water intake system and low-lake-level pumping station in 2008. The adaptation was necessary to ensure that water could be drawn in at lake elevations below 1,000 feet above sea level. The project, completely funded by rate payers, involved excavating a tunnel under Lake Mead and connecting an intake structure secured to the bottom of the lake with more than 1,000 truck-loads of concrete. The third intake was put into service in 2015.

“It’s probably the single largest climate adaptation measure that has happened here,” Pellegrino says.

Technology is also being used in new ways to search for water waste and water theft. For example, SNWA/LVVWD is converting to automated meters to get water flow data every 15 minutes to an hour instead of once a month to detect leaks. “For a single-family residence, if you went three days without shutting off your water, there’s likely a leak. We send a leak detection notice based off of that data,” says Pellegrino. There are also upgrades to filtration systems and plans to create a digital twin of the water system.


The SNWA/LVVWD also worked with the Nevada Legislature to pass a law that makes it illegal to irrigate nonfunctional or decorative turf with water supplied by the Colorado River after 2026. Landscaping will need to be desert friendly and water smart, says Pellegrino. This initiative is projected to save nearly 9.5 billion gallons (30,000 acre-feet) of water. “That’s a program that we financially incentivized for 20 years, but with the drought and the current shortage declaration that era of offering carrots is perhaps over as we get more serious.”

Public outreach and education about water resources and laws around use and rights are essential to making conservation policies and programs effective. “When we build policy, we try to do robust public engagement to ensure that key sectors in the community are aware of the changes that are coming, whether that’s a rate increase or a water conservation package,” she says. “We also tailor our messages to what actions we need customers to take.”

Pellegrino adds, “We all need water, and it’s all of our duty to conserve and use it wisely.”

Conservation Minded

Utah isn’t affected by the current Bureau of Reclamation drought declaration because it sources water from the Colorado River’s upper basin through Lake Powell. But aridification is still a major problem. According to the Utah Division of Water Resources, 2020 was marked as the driest year on record and also one of the hottest.

On March 17, Governor Spencer Cox declared a state of emergency due to drought conditions and has issued two related executive orders since May. Following a record dry summer and fall of 2020, the winter snowpack was about 70% of the yearly average.

Dealing with severe drought conditions may become the norm. “Almost 90% of the state is experiencing extreme or exceptional drought. Even if we start getting some fall rain and snow in the mountains, it [likely] won’t pull us completely out of the drought,” says NSPE member G. Keith Denos, P.E., general manager of the Provo River Water Users Association.

The PRWUA operates and maintains a Bureau of Reclamation water project that provides a supplemental water supply for irrigation of farmlands in the counties of Utah, Salt Lake, Summit and Wasatch, as well as a domestic water supply for communities in northern Utah County and the Salt Lake Valley. The river is home to the Deer Creek Dam and Reservoir, which supplies water to 1.5 million people.

Since 2000, the association hasn’t been guaranteed that it will receive its full annual allotment of water for shareholders. According to Denos, Lake Powell is currently at only one-third of its normal capacity. “If it drops another 50 feet or so, it could compromise the ability to generate power,” he says. “If the trend continues, it doesn’t look good for us.”

Another sign of a difficult future: Utah’s population is projected to double by 2065. A greater demand for water makes it even more urgent to ramp up conservation efforts, including critical infrastructure projects.

In 2011, the PRWUA completed a $150 million canal enclosure project with a large water conservation component. Additionally, a nearly $60 million intake refurbishing project at the Deer Creek Reservoir and Dam, which stores 153,000 acre-feet of water from three river basins, is currently underway. The sustainability project is designed to ensure that the infrastructure is around for another 80 years.

The Utah Division of Water Resources oversees regional goals of reducing water use by 25% by 2025. The region is on track to meet this goal. “We have been preparing because of climate change and getting the users to be more conservation minded,” says Denos.

The Foundation of Public Health

The Phoenix, Arizona, metro area gets water from three different sources to provide for the needs of 1.7 million people: the Salt River, Verde River, and Colorado River. The drought conditions apply only to the Colorado River system, which supplies 40% of the area’s water demand. The Salt and Verde rivers remain full. “Phoenix has been preparing for drought for more than 50 years. We have a diverse water portfolio, with both legal and real rights to more water than what we need to use each year,” says Troy Hayes, P.E., director of the Phoenix Water Services Department.

In January, Arizona’s annual water allocation from Lake Meade will be reduced by 512,000 acre-feet, nearly 18% of the state’s allocation. Because of water conservation efforts by Phoenix, only a level-three drought condition would have a negative impact on delivery to customers. The city treats and delivers only two-thirds of the water allocation, says Hayes, while the other portion is stored in underground aquifers for use only during a shortage.

Water efficiency strategies and education campaigns on living a “desert lifestyle” have led to a 30% per capita per day reduction in water use during the last 20 years despite a population increase of 400,000 people, according to a 2021 Phoenix water resources report.

If there’s one thing that Arizonans understand, says Hayes, it’s the great value of water. “Because water in everybody’s community is the foundation of public health, economic opportunity, and the quality of life, we took it upon ourselves to make sure that we [maintain] a reliable water delivery system.”


An analysis by the Phoenix Water Services Department revealed that the city didn’t have a water resource issue, but rather an infrastructure problem. The utility manages a service area of more than 520 square miles with 7,000 miles of pipeline and 5,000 miles of sewer main, yet one part of the city could be negatively affected by the drought declaration without improvements to the delivery system.

The department is in the midst of a project to construct 11 miles of large water transmission mains and pumping stations to better facilitate water delivery wherever and whenever it’s needed. The first steps to solving this delivery problem involved getting buy-in from the city council and the community. “When everybody understood the issues and what we are trying to accomplish, it wasn’t difficult to get them to embrace overcoming this challenge,” says Hayes. “They voted and adopted new water rates to pay for the infrastructure.”

Project completion and operation is anticipated by early 2023. “Once we get that infrastructure in place, we will be in a really good spot to go decades into the future,” says Hayes.

The department also maintains an asset management-based approach to ensure that capital program dollars are put in the right place at the right time with rehabilitating and replacing old infrastructure to improve water efficiency. There are also ongoing discussions with local municipalities to consider constructing new dams to capture water during wetter periods for later use.

None of these capital program projects could come to fruition without a dedicated team of licensed engineers and technical professionals, says Hayes. “We are trained to be problem solvers and overcome challenges. This couldn’t have been overcome without our engineers and the AEC consultants.”