Bartlett Dam and Reservoir Expansion Project
SRP is working to restore and increase storage capacity along the Verde River at Bartlett Lake to help protect the Valley’s water supply for generations to come.
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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.
In 2023, SRP had to release water from Bartlett as the reservoir reached capacity due to heavy winter precipitation in the Verde watershed. SRP released enough excess water from Verde reservoirs during that time to meet the needs of over 1 million households for an entire year.
The solution: Expanding Bartlett Dam
SRP is constantly evaluating ways to ensure that there is enough water to support our growing population while also planning for changing climate conditions. During a recent study along the Verde River, SRP’s engineers identified possible solutions that could protect the water supply and help increase total water storage. The most promising solution is to expand the size of Bartlett Dam to enlarge the reservoir’s capacity and update operating plans to better manage sediment buildup. The concept to modify Bartlett Dam and Reservoir came through an early planning study led by the Bureau of Reclamation. Section 40902 of the Infrastructure Investment and Jobs Act, P.L. 117-58 (Bipartisan Infrastructure Law [BIL]) granted authorization for the consideration of modifying Bartlett Dam and Reservoir under the Verde Reservoir Sediment Mitigation Project Federal Feasibility Study.
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, the Bartlett expansion will 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.
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
SRP and 22 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.
Funding the project
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 22 funding partners. If construction is approved, 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 expansion project is expected to take 10–15 years to complete and will help secure more water in the Valley for generations to come.
Want more information? Check out our in-depth water resiliency article or read the FAQ below to learn more about this project.
Sedimentation has reduced storage capacity in the Verde River reservoirs by approximately 45,000 acre-feet (af). Expanding Bartlett Dam would help restore and increase the capacity of Horseshoe and Bartlett reservoirs by creating a single reservoir on the Verde River. Additional water storage will help support our growing population and prepare for the Valley’s drought periods, which are expected to last longer as the climate changes.
Yes. In the 1990s, SRP successfully modified the Roosevelt Dam along the Salt River. The $430 million project increased the height of the dam by 77 feet, more than doubling Roosevelt Lake's capacity and creating additional water supplies to serve more than 850,000 households per year.
SRP is partnering with 22 municipal, tribal and agricultural partners. See the full list below.
- Apache Junction Water District
- Arizona Water Company
- Buckeye Water Conservation and Drainage District
- Carefree Water Company
- Central Arizona Groundwater Replenishment District
- City of Avondale
- City of Buckeye
- City of Chandler
- City of El Mirage
- City of Glendale
- City of Goodyear
- City of Mesa
- City of Peoria
- City of Phoenix
- City of Scottsdale
- City of Surprise
- City of Tempe
- EPCOR Water
- Fort McDowell Yavapai Nation
- Pinal County Water Augmentation Authority
- Town of Gilbert
- Town of Queen Creek
SRP and the other funding partners are working with the Bureau of Reclamation to complete a federal feasibility study to evaluate the proposal to expand Bartlett Dam and Reservoir. We expect to send the report to the U.S. Congress by late 2026. Congress will then vote to determine if the project should be approved.
The anticipated cost of this feasibility study, including the engineering and design of the facilities and environmental compliance, is $28 million. Half of that cost will be covered by the federal government, with the other half split among SRP and the 22 partners. The expansion 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 and no single partner is expected to pay the bulk of the costs of the project on their own.
While project details are still being evaluated, this project could take 10–15 years to complete. The next step following the feasibility study is getting congressional approval. More details about the project timeline will be shared as they become available.
SRP is always working to ensure a reliable water supply for the Valley. While there is enough water now, we must plan to meet the needs of central Arizona’s growing population. This project would help optimize water supplies for the future and also help better prepare the Valley for the challenges that come with a changing climate.
Aside from protecting the Valley’s water supply, this project will have a variety of other positive effects, which include expanding riparian wildlife habitat (especially for bird species) and increasing recreational opportunities that help stimulate Arizona’s economy.