Flowing more than 2,300 km from source to sea, the Colorado River is a vital watershed for the United States and provides drinking water to millions of people. Conflicts over the Colorado River basin began in the early 1900s, and today with so many communities relying on this water source, managing the river equitably continues to be a challenge.

By: Dr. Kathy Freas, CH2M HILL Global Water Resources and Ecosystem Director

For more than a century, the Colorado River basin has been a hotbed for conflict as stakeholders and resource management entities such as the federal Government, Native American tribes and communities, state agencies, municipalities and agricultural districts, advocacy groups, non-governmental organizations and local governments have attempted to equitably manage this vital water source. The River—which drains a basin of about 637,000 square kilometers and covers roughly a twelfth of the contiguous United States—provides drinking water to 40 million people; irrigates 5.5 million acres of farmland; and fuels hydropower facilities that generate more than 4,200 megawatts of power and provides myriad habitats, supporting threatened and endanger species.

In the early 1900s, numerous compacts, treaties and other agreements were made that collectively comprise the ‘Law of the River’; however, these arrangements were based on a limited flow record—one that doesn’t reflect the long-term average annual yield of the River. With over allocation and drought to blame, complications arise when communities lack access to water supplies.

With climate change threatening to intensify the water challenge, the U.S. Department of Interior launched numerous programs to focus on climate adaptation and long-term planning for the Colorado River basin. Reclamation began developing a computer model of the basin nearly 35 years ago, known as the Colorado River Simulation System (CRSS). Over the years, the model has evolved to improve usability and adapt for the ever-changing dynamic of the basin.

In 2010, Reclamation and the seven U.S. basin states (Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming) commenced the Colorado River Basin Water Supply and Demand Study to identify potential supply and demand imbalances facing the Colorado River basin over the next 50 years, as well as potential solutions.

The study focused on four major components, including:

  • Future supply (hydrologic conditions)
  • Future demand
  • Evaluation of options and strategies
  • And vulnerability analysis.

Private sector firms, including CH2M HILL, contributed to the study, providing technical expertise, analysis, and report production. Leveraging multi-stakeholder work groups, the first phase of the study provided a comprehensive view of the issues and resulted in creative solutions for numerous supply and demand scenarios. The study resulted in 4 supply scenarios based on mean flow, variability and drought magnitude and persistence. Demand scenarios took into consideration variables such as the economy, population growth and location, environmental awareness, and farming practices. In the end, 6 demand scenarios were agreed upon.

Taking the supply and demand findings, the next phase of the study involved the general public through extensive outreach programs to solicit input on how to resolve the imbalances identified. By engaging the public, the team received more than 150 submissions providing solutions from augmentation to water conservation to alternative management approaches. The options were grouped based on cost, reliability and energy needs to implement the solution.

In the final phase of the study, the team conducted a vulnerability analysis using the CRSS model to evaluate water deliveries, hydropower, recreation, ecological resources, water quality and flood control. After taking into consideration all of the proposed solutions, the study confirmed the benefits of coordinating a comprehensive preventative strategy to manage such a complex river basin.

There is still more work to be done, but the success of the supply and demand study is a positive first step to managing the risk and imbalance in the basin.

You can learn more about this study in the Free Flow—Reaching Water Security Through Cooperation article (pg. 115) released during the Budapest Water Summit or on the U.S. Bureau of Reclamation’s website.

Dr. Kathy Freas, CH2M HILL Global Water Resources and Ecosystem Director, served as the senior technical advisor/project sponsor on the Colorado River Basin Water Supply and Demand Study, Part 1; U.S. Bureau of Reclamation. She has been leading CH2M HILL’s climate change initiative, which guides the development of tools and approaches for addressing greenhouse gas management and water-related adaptation. Her expertise lies in the integration of science and engineering to develop implementable solutions for technically complex and politically sensitive water resources and environment challenges, particularly the effects of climate change. Dr. Freas has 26 years of water resources and ecosystems management experience, 10 of which have been focused on climate change effects.