Verde Reservoirs Sediment Mitigation Project

The need: Restoring lost capacity and increasing water supply

For decades, SRP has been partnering to manage a 13,000-square-mile watershed — an area of land where rain and melted snow drain into creeks and rivers. This water flows into the Salt and Verde rivers where dams operated by SRP form vital reservoirs. Like water, sediment is naturally transported through the Verde River and ultimately makes it to these reservoirs. Over time, this sediment builds up, reducing the overall amount of water that can be stored. These reservoirs, which you may know as lakes, store water for when the Valley needs it most.

Water storage along the Verde River

Northeast of Phoenix along the Verde River, SRP manages two dams and their corresponding reservoirs: Horseshoe and Bartlett. During wet winters, reservoirs are more likely to reach capacity, which requires SRP to release excess water that could have otherwise been stored for use during the dryer months and years.

A solution: Expanding Bartlett Dam

SRP is constantly evaluating ways to ensure that we are effectively and sustainably managing the Valley’s water supply while also planning for changing climate conditions. The Bureau of Reclamation coordinated and finalized the Verde Reservoirs Sediment Mitigation Study Appraisal Report in December 2021 to identify possible solutions that could help protect the water supply and restore water storage capacity lost to sedimentation. One promising solution identified in the report involves the expansion of Bartlett Dam to enlarge the reservoir’s capacity as well as updating operating plans to better manage sediment buildup. Section 40902 of the Infrastructure Investment and Jobs Act, P.L. 117-58 (Bipartisan Infrastructure Law [BIL]) granted authorization for the Verde Reservoirs Sediment Mitigation Project Federal Feasibility Study to further evaluate solutions for addressing sedimentation and lost capacity at the Verde River reservoirs. An expanded Bartlett Dam and Reservoir is one proposed solution that will be evaluated through the feasibility study.

Project benefits

By expanding Bartlett Dam, the reservoir will be able to capture more water during wet winters. This means there will be more water available to use during drought periods, which are expected to last longer on average over time. Along with an expansion of Bartlett Dam, changes to reservoir operations will help SRP better manage sediment that flows into the reservoirs during large flood events. The water supplies made available by the project will help central Arizona manage shortage conditions on the Colorado River and help reduce our reliance on nonrenewable water supplies like groundwater.

While details are still being evaluated, the most effective solution would be to raise Bartlett Dam by about 100 feet. SRP completed a similar expansion project at Roosevelt Dam in the 1990s, which successfully increased reservoir capacity. At Bartlett, the additional capacity gained under the proposed plan would equate to a year’s worth of water for a million homes.

Supporting Colorado River shortages

SRP is committed to identifying ways to strategically manage regional water supplies for the benefit of all. In addition to protecting water for SRP customers, a potential expansion of Bartlett Dam would be essential to bringing new supplies of water to central Arizona that can help alleviate the current shortages on the Colorado River, another major source of water for the Valley.

Additional benefits

Aside from protecting the Valley’s water supply, this project will have a variety of other positive effects, which include:

• Potentially benefiting local wildlife by expanding riparian habitats, especially for bird species
• Increasing recreational opportunities that stimulate Arizona’s economy
• Improving SRP’s ability to balance safe flood operations and water storage

Next steps

SRP and 23 municipal, tribal and agricultural partners are working with the Bureau of Reclamation to complete a feasibility study that evaluates the proposal to expand Bartlett Dam. Following the study, a finalized plan will be presented to the U.S. Congress for consideration. Congress will then hold a vote to determine if the project should be approved.

A test quarry study near Bartlett Dam, managed by Kiewit Construction Company, began in late August 2024 and will run until late January 2025. This study, part of the Verde Reservoirs Sediment Mitigation Project, involves targeted detonations to remove rock from a specific area on the south shore of Bartlett Reservoir. The extracted rock will be transported to the Jojoba Boat Ramp and then taken off-site for further study. The purpose of the test quarry study is to evaluate the feasibility of the on-site rock to be used as construction material. This will not disrupt water delivery to over 2.5 million Valley residents who receive water from SRP. To learn more about the test quarry, including information on impacted areas and the timeline, please refer to the test quarry fact sheet.

Funding the Feasibility Study

The anticipated cost of this feasibility study is $28 million. Half of that cost will be covered by the federal government, with the other half split among SRP and the 23 funding partners. If construction of a feasibility study alternative is approved by Congress, the total project is estimated to cost around $1 billion. The construction costs will be shared among those benefiting from the project and will be determined through the completion of the feasibility study. The potential expansion of Bartlett Dam is anticipated to take 10–15 years to complete and will help secure more water in the Valley for generations to come.

FAQ

Want more information? Check out our in-depth water resiliency article or read the FAQ below to learn more about this project.