UNIVERSITY PARK, Pa. — Key agreements in the “Law of the River,” which encompasses more than 100 years of regulations, laws, court decisions and more focused on managing the Colorado River, are set to expire next year. First established in 1922 as the Colorado River Compact, the guidelines split water management and allocation among seven states. Now, those states — Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming — are renegotiating the terms of use for the water. Drought, increased temperatures and decreased snowpack in the Rocky Mountains are complicating the matter, according to Antonia Hadjimichael, assistant professor of geosciences at Penn State.
Hadjimichael, an interdisciplinary Earth scientist, studies how climate impacts water resources. A lot of her work focuses on the Colorado River because she said it serves as a “fascinating case study” of how climate, water, human institutions, economics and infrastructure interact. She specifically uses mathematical modeling, artificial intelligence tools, visual analytics and high-performance computing to investigate how critical water resources might change in the future and how society can plan ahead to minimize negative impacts.
In this Q&A, Hadjimichael spoke about the Colorado River, its challenges and the research that looks to make the river a sustainable resource for millions of people.
Q: Why is the Colorado River considered so complex?
Hadjimichael: The Colorado River is divided up in multiple ways to supply water for people, land irrigation, industries, cities and ecosystems. It’s a vital but limited resource for many, and decisions made by one agency or user can have ripple effects on others. This complexity makes it an incredibly engaging challenge from a scientific perspective while also being an urgent societal issue.
Q: What makes the Colorado River so important?
Hadjimichael: The Colorado River impacts seven states and even crosses international borders into Mexico. What we do in the U.S. affects another country as well. It is emblematic of American water issues, involving tribal rights, historical water rights from early Western expansion and the challenge of sustaining large cities in the middle of the desert while also supporting agricultural communities that feed the nation and the world. Its influence spans far beyond the Southwest.
Q: How many people rely on the Colorado River?
Hadjimichael: The Colorado River provides water for approximately 40 million people. Major urban centers such as Denver, Los Angeles and Las Vegas depend on its water, as do numerous agricultural communities and industries. Some small villages exist solely because of the water provided by the river. Additionally, tribal communities with long histories in the region also rely on its water, and the ongoing water struggles affect them as well.
Q: What are the biggest challenges facing the river today?
Hadjimichael: The primary challenge is how water is allocated. The Colorado River Compact, established more than 100 years ago, divided the river’s water between the upper and lower basin states. However, the compact overestimated the river’s water supply, allocating more water than what is actually available. This issue has been exacerbated by a two-decade-long drought, meaning that not only did we never have as much water as planned, but we now have even less. Reservoirs are at historic lows, and at the same time, demand is increasing due to higher temperatures and drier conditions. Everyone feels they are not getting what they were promised, creating tensions among stakeholders.
Q: What role does climate change, including drought, play in these challenges?
Hadjimichael: Climate change drives extreme weather events, like prolonged drought, as well as longer term issues like the region becoming increasingly drier over time, both of which exacerbate water scarcity in the Colorado River Basin. Higher temperatures lead to increased evaporation, drier soils and higher water demands from crops and ecosystems. This compounds the issue of overallocation, making an already unsustainable system even more strained.
Q: How are people addressing these issues?
Hadjimichael: Various management efforts exist at different levels. The Bureau of Reclamation oversees reservoirs and negotiates with states. Within individual states, water conservation boards and resource divisions work to determine the best ways to use and conserve water. Conservation efforts target both municipal and agricultural use. Cities have programs to reduce water consumption, while farmers are incentivized to adopt more efficient irrigation methods, sometimes receiving financial compensation to divert less water from the river.
Q: Are conservation efforts making a difference?
Hadjimichael: Yes, conservation efforts help, but they are often temporary measures. For example, paying farmers to use less water for a season can provide short-term relief, but long-term solutions are needed. Some efforts, such as switching to more efficient irrigation methods, have lasting benefits, but ultimately, the entire system needs to be reconsidered for sustainable water use in the future.
Q: What are some key highlights of your research on the Colorado River?
Hadjimichael: A lot of our work focuses on the Upper Colorado River Basin within Colorado. We study how different water users with varying rights are affected by drought and how their actions impact others. If one user diverts water, it changes availability for others, which makes managing the system incredibly complex. Understanding these dynamics informs better strategies for sustainable water management in the future.
Q: What’s the main takeaway about the Colorado River’s future?
Hadjimichael: The Colorado River is an already stressed system, and we are at a critical point where every drop matters. While conservation and management efforts help, the reality is that we are dealing with a resource that has been overallocated and is being further strained by climate change. Continued cooperation, innovation and difficult decision-making will be necessary to ensure its sustainability for future generations.
Editor’s note: See more of Hadjimichael's publications on the Colorado River. This Q&A originally appeared as an Institute of Energy and the Environment blog.