Water authorities in the Western U.S. don’t know what the future will bring, but they are working collaboratively and with scientific rigor to make sure they’re prepared for anything.

Editor’s note: This story is part of a four-part series — “Hotter, Drier, Smarter: Managing Western Water in a Changing Climate” — about innovative approaches to water management in the U.S. West and Western tribal nations. The series is supported by The Water Desk , an independent journalism initiative based at the University of Colorado Boulder’s Center for Environmental Journalism. You can read the other stories in the series, along with more drinking water reporting, here.

In a thirsty Western United States that has become increasingly vulnerable to extreme weather events, rampant wildfires and years of unprecedented drought, those at the helm of the region’s water agencies are accelerating their plans to grapple with climate change.

“The Western United States — especially the 40 million people who use the Colorado River — we’re in the bullseye of climate change,” says Cynthia Campbell, water resource management advisor for the City of Phoenix. “This is not a conceptual conversation anymore. We’re in full-on adaptation.”

With that reality comes the need to plan around the future of water for the people and wildlife who call the Colorado River Basin home.

But, says Carly Jerla, an operations research analyst for the United States Bureau of Reclamation’s Lower Colorado Region, “you can’t just plan for one future.”

As climate change casts its shadow over water resources in the Western U.S., water authorities must navigate uncertainty in the form of the many possible futures in front of them. Those futures almost certainly hold more of what climate change has already brought — rising temperatures, changes in precipitation, shifts in snowpack, longer and more severe droughts, more frequent flooding — plus people’s responses to those changes. Taken together, these fateful forecasts go into climate projections: models that explore an array of possible future climate conditions or scenarios.

Today, planning agencies are working together to diversify the technology they’re using and integrate scientific research into local and regional adaptation strategies in an effort to be rigorous in their analysis of the uncertainty.

Adapting to climate change “shouldn’t be scatter-shot,” Campbell says. “It can actually be more scientific.”

Mix of Solutions

Although local regulations vary among Western water agencies, the inclusion of climate projections into authorities’ planning processes has become all but universal. Grappling with uncertainty requires water managers to account for supply and demand challenges that are (and will be) driven by climate change, says Jerla, who is currently stationed at the University of Colorado Boulder. On the supply side, she explains, are factors such as higher temperatures, precipitation and snowpack changes, and droughts and flooding. Shifts in demand, meanwhile, are from things like rising evapotranspiration rates in agriculture and impacts to residential irrigation.

A longtime expert on modeling applications and planning operations for the Lower Colorado Region, Jerla was the study manager for the Bureau of Reclamation’s Colorado River Basin Water Supply and Demand Study. The assessment was completed in 2012, and its technical foundations helped guide climate adaptation policies. The research, which occurred under the umbrella of the agency’s larger Basin Study Program, quantified water imbalances through 2060 and suggested potential strategies for mitigation and adaptation.

The study identified shortfalls between projected supplies and projected demand in the Colorado River Basin by looking at a range of possible future climatic scenarios and analyzing many possible outcomes, according to Jerla. One particular scenario, called a downscaled general circulation model (GCM), forecasted that as the climate continues to warm, the mean natural flow of the Colorado River at Lees Ferry, Arizona — significant because it’s the point that separates the river’s Upper and Lower Basin, and from which water allocations for the Basin states are determined depending on river measurements — would decrease by about 9% over the next 50 years, alongside longer, more frequent droughts.

“One of the things that this opened our eyes to is the importance of communicating the uncertainty with respect to future outcomes, especially when you’re looking 50 years in the future,” Jerla says.

In addition to examining these scenarios, she and her colleagues evaluated adaptation and mitigation strategies that might reduce supply and demand imbalance. One important conclusion, according to Jerla, was the notion that water agencies would need to diversify their portfolios to include a variety of mechanisms like water reuse, desalination and increased water transfers to urban areas.

“There was no one solution that was going to be a fix-it,” Jerla says. “It has to be a mix of stakeholders involved.”

A Critical Period

The next few years will be a critical policy planning period for Western water agencies, culminating in the particularly pivotal year of 2026. The drought contingency plans for the Upper and Lower Basins of the Colorado River, which have helped further the understanding that the status quo is no longer sustainable, will expire that year and likely undergo significant changes. In the plans, first approved by Congress in 2019, the seven Colorado River Basin states committed to protect the water levels of Lake Powell and Lake Mead — the human-made reservoirs that store Colorado River water and serve the basin states — through various conservation mechanisms.

Not only will the Colorado River Drought Contingency Plan expire in 2026, so too will the 2007 Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead, as well as the terms of the International Boundary and Water Commission’s Minute 323 — an updated “implementing agreement” of the Mexican Water Treaty of 1944 that established U.S.-Mexico protocols for collaborative management of the Colorado River. Experts agree that new negotiations on the interim guidelines, as well as between the U.S. and Mexico on a new Minute, will be instrumental in shaping collaborative water management for the future, which will no doubt involve serious consideration of climate change projections.

“In the Colorado River Basin, we’ve been at work really since the Interim Guidelines for Powell and Mead Operations, since 2007, slowly building and adding to our operational decisions, planning efforts, policies — all with a mind toward more flexibility, enhanced resiliency, preparing for the challenges ahead, building science into the activities,” Jerla says.

For the Colorado River, Jerla and her colleagues have been making projections about relevant reservoir elevations through 2025, as they know what the operational guidelines will be until 2026. Generating such projections and sharing them with their local and regional partners remains crucial in order to help stakeholders understand what water reductions they might need to make.

Jerla says she is confident in the “robust set of policies” in place through 2026, which specify the water reductions that both U.S. states and Mexico will need to implement when the basins reach specified levels. Although she acknowledges the “dismal hydrology” that the region will likely encounter for the next five years, Jerla expresses hope that through “the spirit of cooperation the basin will come together.”

A Collaborative Approach

Beyond 2026, once new guidelines are in place, Jerla says she envisions more collaborative decision-making, more incorporation of science and more involvement from area tribes and Mexico as the region embraces new action plans for coping with a drier future.

While the Bureau of Reclamation has taken responsibility for many of the climate modeling efforts and continues to work collaboratively with local programs, it is the states that “have the most primary responsibility for allocating and receiving the water in their own state,” with their own sets of water laws and systems, Jerla explains. Down another level, she adds, local government authorities, urban municipalities, water councils and water associations employ the state regulations to manage water supplies on a local level. As a federal body, the Bureau’s role is to facilitate agreements across state boundaries — a process that has largely gone smoothly through mutual consensus.

“All the states have interests and priorities,” says Amy Ostdiek, deputy section chief at the Colorado Water Conservation Board, a cohort appointed by the governor to represent each major Colorado basin and relevant state agencies. “The Colorado River ties us together.”

As demands have continued to shift, the Colorado River Basin states have been “negotiating and renegotiating,” with a keen interest in furthering collaborative solutions, Ostdiek says. The Bureau of Reclamation, she explains, has always played a key role in this process, but planning occurs at the state level.

Individual states are now implementing the commitments made in the 2019 Drought Contingency Plan. Upper Basin states, which sit upriver from the Lower Basin states and are therefore responsible for not depleting the flow of the Colorado River, are focused on planning for a future with less water. Colorado itself sits at the headwaters of the river and is exploring options such as temporary compensated reduction of use, in which water users could get paid for using less water, Ostdiek explains.

Internally, state water agencies also have individual programs that focus on a sustainable future, such as the 2015 Colorado Water Plan. The Water Plan was Colorado’s first such program and in its first five years funded more than 241 water projects, such as infrastructure improvements, irrigation efficiency measures and engagement projects like taking science teachers on a five-day trip of the Rio Grande to show them various water issues facing Colorado. Set to be updated in 2022, the Water Plan builds upon previous supply planning and projects how much water the state will need in the future, according to Megan Holcomb, climate change risk management specialist at the Colorado Water Conservation Board.

A recent pilot initiative of the Water Conservation Board, the Future Avoided Cost Explorer (FACE:Hazards), aims to anticipate Colorado’s economic impacts from flood, drought and wildfires in 2050. The study, funded predominantly by the Federal Emergency Management Agency, according to Holcomb, paired four population scenarios (ranging from current population to high growth) with three climate scenarios (current, moderate and more severe change). The authors then discussed actions that Coloradans could take to reduce economic impacts from these hazards, as well as the relative cost associated with each action.

“If we can quantify what impacts from climate change will be without any action, then we have a baseline to say why resilience investments are worthwhile now,” Holcomb says.

Another internal Coloradan water program that takes climate change into account is the Drought Task Force, which is able to recommend mitigation measures as necessary statewide. While the governor makes the ultimate decision regarding these measures, the Task Force involves representatives from departments of natural resources, public safety and agriculture, among others.

Moving forward, both Ostdiek and Holcomb say that operational flexibility and a willingness to adopt creative solutions will be key to coping with climate change in water planning. Due to Colorado’s unique headwater position — which already limits how much Colorado River water the state is entitled to each year — Holcomb argues that Colorado needs to be particularly creative about water rights by furthering innovative tools like water leasing, which allows water rights holders to lease their water to other users.

Collaboration and scientific rigor are key, all these experts agree, to making sure the region is as prepared as possible for any future that may present itself.

“We can all acknowledge that we need to be able to share within the state as well,” she says.

At the other end of the Colorado River Basin, water officials in Phoenix, Arizona, are recognizing that some 40% of the city’s water supply may be in jeopardy due to climate change, according to Campbell from Phoenix Water.

That’s one reason, Campbell explains, planners in Arizona are observing shifts in the flow pattern of the Colorado River that are the direct result of climate change. She and her colleagues are strategizing how they might replace the supplies that are in jeopardy — looking at exact times and places where reductions can be made through “targeted demand management.”

For example, Campbell suggests, a project could work to reduce the amount of water used by cooling towers at a power plant by studying the precise impact of changing the water used by certain towers. Such adaptation tactics, according to Campbell, would have a much more significant impact than, for example, shutting off the water while brushing teeth — a practice that, while good for conservation, is “not going to yield the type of water we’re talking about.”

And because the amounts of water experts are talking about are not set in stone, dealing with that uncertainty will continue to be a critical responsibility of water agencies going forward. Collaboration and scientific rigor are key, all these experts agree, to making sure the region is as prepared as possible for any future that may present itself.

Editor’s note: The main image is courtesy of the U.S. Department of the Interior. The original can be found here