The Cat Creek Energy & Water project (CCEW) is a major pumped storage and renewable energy generation project that is scheduled to be built north of Mountain Home, Idaho, on the South Fork of the Boise River. The project, which will use the Bureau of Reclamation’s Anderson Ranch Reservoir as its lower reservoir, will have a total of 1,100 megawatts (MW) of generation capacity—380 MW of on- and offsite wind and solar and 720 MW of pumped storage hydropower—and its large upper reservoir will be able to support 5 full days of full hydropower generation. In addition to the obvious benefits of power storage and generation, CCEW’s design will provide additional water storage to a region that needs it, particularly as reductions in snowpack affect its yearly water supplies, and it could even help avoid a cutoff in water supplies during a potential dam raise at Anderson Ranch Dam. In this interview, CCEW’s public policy advisor, Peggy Beltrone, updates us on the project’s progress. 

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Hydro Leader: Please introduce CCEW. 

Peggy Beltrone: CCEW delivers simultaneous daily and multiday energy storage through an advanced configuration of pumped storage hydropower. It is also an important water storage facility for southwestern Idaho. The project will pair the existing federal Anderson Ranch Reservoir with a new upper reservoir on private ranchlands. Its sheer scale, customized ternary hydro turbine technology, advanced electronics, and dual mission distinguish it from other pumped storage hydropower projects. Combined with its sister variable renewable energy resource component, CCEW will become Idaho’s largest electricity generator, providing a nameplate capacity of 980 MW of renewable power generation. With an additional 120 MW of offsite generation under our ownership, CCEWs total capacity is 1,100 MW. The facility will be a vital tool in the transition to a carbon-free electrical grid with over 3,000 gigawatt-hours of energy production annually and 87,120 megawatt-hours of large-volume, long-duration energy storage. CCEW’s new reservoir will increase the Boise River system’s water storage by a whopping 10 percent, enabling water to be put to multiple beneficial uses downstream and promoting the burgeoning growth of the Treasure Valley. 

Hydro Leader: What convinced you to add a water storage component to CCEW? 

Peggy Beltrone: Here is the problem: Every climate model for the Pacific Northwest, and for southwestern Idaho in particular, predicts increasing temperatures over the next 50 years, even if global warming can be limited to 1.5 degrees centigrade. As a result, there will be less snowpack, which serves as the largest water storage system in the Northwest. There will be more winter rains; snow will melt earlier; the warmer weather will lengthen the growing season by a month on average; and without significant new storage, there will be less irrigation water available. Paradoxically, the annual average amount of precipitation is forecast to grow around 9 percent in the Upper Boise River basin, making harmful earlier-season flooding more and more probable. We’ve seen such flooding occur over the past 5 years in Idaho, Oregon, and especially Washington. The obvious way out of this paradox is to store excess runoff in the spring, mitigating flood damage, and release it later in the summer, when it is much needed for irrigation. We have already signed memorandums of understanding with forward-looking irrigation districts and municipalities downstream from our project. 

Hydro Leader: Please tell us about the current status of CCEW. What recent progress has been made? 

Peggy Beltrone: Progress has been steady. With local permitting secure, we are now well into the federal permitting slipstream. We are advancing our preferred federal hydropower licensing plan, working through our water rights applications, and deciding on our technology acquisition. Our interconnections are secured. That places the project at precisely the right pace to reach commercial operation when the western transmission grid is seeking new grid stabilization services to replace fossil-fuel generators and can take advantage of what CCEW offers for the clean energy transition. Our location provides the entire West a solar and wind daily overproduction sink. Our large storage capabilities, exceptional generation, and power services mean that our facility covers all the requirements of the energy evolution. 

A cross section of the Voith Hydro ternary units to be used in the Cat Creek project.

We have advanced the hydropower licensing and water supply process within the past month by filing a 241‑page preapplication document with the Federal Energy Regulatory Commission (FERC) and an equally extensive draft work plan with the Bureau of Reclamation. The FERC submission is required for a license to operate; the Reclamation submission, for a lease of power privilege authorization to use Anderson Ranch Reservoir as our lower reservoir. The documents submitted describe the proposed facilities, contain information on the natural resources that are affected, and give a preliminary analysis of the effects of operation. Due to the special location of CCEW’s new reservoir, CCEW was able to apply to the State of Idaho for a right to previously unallocated spring flows to fill the CCEW reservoir storage facility. 

Hydro Leader: Please tell us about recent policy and market changes related to long-duration energy storage and how they stand to affect CCEW. 

Peggy Beltrone: State and corporate clean energy goals continue to drive the long-duration energy storage market. There is growing acknowledgement that long-duration storage and generation technologies, such as pumped storage hydropower, are crucial for reaching a decarbonized economy. Such long-duration energy storage is indispensable if variable renewable energy resources—principally wind and solar—are to make up a dramatically increased share of electricity generation. For example, Strategen Consulting found that progress toward California’s goal of 60 percent renewable energy by 2045 will require 2–11 gigawatts of long-duration energy storage by 2030 and 45–55 gigawatts by 2045. State regulators in California and elsewhere are requiring utilities to add this vital storage to their portfolios. Elsewhere in the Northwest, firm decarbonization goals have also been set by both legislatures and utilities themselves. Idaho Power Company, for example, has announced a goal of 100 percent clean energy by 2045. Additionally, growing evidence that meeting climate and clean energy goals will require additional and longer-duration energy storage has led to an uptick in private investment in a host of long-duration energy storage projects and technologies. Given its unrivaled location at a multidirection transmission hub, CCEW can serve markets all over the West. 

As a result of continuing drought conditions in the West, there are calls for increased water storage. Offstream pumped storage facilities that involve an existing reservoir can address this water storage need cost effectively while also providing the most efficient, economical, and long-term method for regulating the grid. 

Hydro Leader: Have there been changes in the public perception of the value of new pumped storage projects?

Peggy Beltrone: Several years ago, I noticed that the national labs and universities were digging deeper into pumped storage. It is, after all, the most widely used, thoroughly tested, and cost-competitive energy storage technology available. It accounts for roughly 95 percent of the world’s electrical energy storage and has been thoroughly tested over the past 100 years. This increased attention coincides with the increased development of pumped storage hydropower. A dozen years ago, FERC had granted 39 preliminary and pending permits for pumped storage hydropower. Today, the total is 91. And there’s an uptick in stories about pumped storage hydropower in traditional news outlets. All of this drives interest from regulators, advocates, and policymakers. Whereas pumped storage hydropower facilities were once one-off construction projects, many have been proposed today, and only a few, such as CCEW, can serve the dual purpose of new water storage in addition to power storage and generation. 

Hydro Leader: Please tell us about the discussions of raising the level of Anderson Ranch Reservoir. 

Peggy Beltrone: One would expect raising a dam by only 6 feet to be a simple exercise, especially since at the time when it was built, Anderson Ranch Dam was the tallest earthen dam in the world. But the process of doing so is quite involved, and Reclamation is fastidious about making sure that all consequences of a raise are addressed. In this case, the effect on shoreline areas and the modification of the infrastructure surrounding those areas has been addressed, as have the questions of traffic over the dam during its construction and the effects on recreation. 

The nagging problem is that during those construction years, less water will be available to downstream irrigators, many of whom raise some of the world’s most vital seed crops. According to Reclamation, the Anderson Ranch Dam raise will require a drawdown and reduction in overall water availability for downstream agricultural uses for at least three growing seasons. Downstream irrigators might lose as much as 97,000 acre-feet a year during the dam raise. Sources say that the irrigators do not want cash to offset their losses, but water to continue their operations during this minimum-3‑year period. 

CCEW could provide an immense benefit to these ag producers by using its new reservoir to replace the water storage of Anderson Ranch Reservoir during the construction project to raise Anderson Ranch Dam. If Cat Creek Reservoir is built before the dam raise, even before our powerhouse and other appurtenances are complete, it could store and deliver that water, resolving a major hurdle for the dam raise and preserving those irreplaceable irrigated farmlands, which otherwise would go dry and take up to an additional 3 years to fully reconstitute themselves. 

Hydro Leader: In what other ways will CCEW’s water storage component benefit Idaho? 

Peggy Beltrone: Using new water storage, rather than additional groundwater, to increase the Treasure Valley’s water supply will facilitate the region’s expansion while allowing it to continue to irrigate the seed crops it sells around the world. In addition to the needs of irrigation, resources are required to support the economic expansion of the Treasure Valley. For example, tech giant Micron is deciding where to expand its facilities. It is a major investment. A facility like CCEW can ensure both the water necessary for its expansion and net-zero-emission energy for its sustainability mission. 

Hydro Leader: Where are we in the timeline of the construction of Cat Creek? What are the next steps that need to be taken? 

Peggy Beltrone: We expect the building of wind and solar modules to commence in 2022. We anticipate a clearly defined process with FERC that will allow us to complete the full pumped storage hydropower facility and begin commercial operation by the end of 2026 or early 2027. The earlier FERC can approve the facility and CCEW can commence the formal lease of power privilege with Reclamation, the better the chances that we can complete the reservoir earlier, thus allowing us to provide water storage during the Anderson Ranch Dam raise cycle. 

Hydro Leader: How has public perception of the Cat Creek project changed? What public communications efforts are you carrying out? 

Peggy Beltrone: We have updated our communication plan to reach more people more often. This involves a refreshed web presence at and more targeted communications. We have entered a phase in our long development cycle in which we can respond more specifically to questions. It is a difficult to keep a project in the public eye when there are long periods between milestones, but now, with technology partners aboard, designs locked in, and federal review underway, all is changing rapidly. The hard part is getting people to see that CCEW is more than just another pumped storage hydropower project, not simply because it stores more energy for longer periods of time than any other pumped storage hydropower project (or for that matter, any other chemical battery project), but also because it stores large amounts of increasingly needed water in a drought-stricken part of the country and is also uniquely able to ensure the resource adequacy, capacity flexibility, and grid resiliency required by a decarbonized 21st-century electricity transmission system. 

Peggy Beltrone is the public policy advisor for Cat Creek Energy & Water. She can be contacted at For more on CCEW, visit