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Hydropower is critically important to a reliable carbon-free grid, but the future of hydropower relies on coupling reliable, flexible power production with technology and practices that maintain and restore healthy river ecosystems.
The Monroe Drop project, located in central Oregon, provides a compelling case study of how hydropower can prioritize both efficiency and sustainability.
With novel safe fish passage and high-performance hydropower sourced from pre-existing infrastructure, the Monroe Drop project also provides insight to owners and operators looking to learn from the project’s fish passage data – studies conducted in 2020 and 2022 demonstrated that the site’s turbines passed rainbow trout up to 19.7 inches with 98-100% survival and no detectable injuries.
INNOVATIVE USE OF EXISTING INFRASTRUCTURE
Situated in Oregon’s Deschutes River Basin, the Monroe Drop project makes use of a pre-existing irrigation canal operated by the North Unit Irrigation District. Originally designed to deliver water to nearly 50,000 acres of farmland, the canal now also serves as a renewable energy source.
In 2020, Natel, an engineering company specializing in hydraulic design of turbines designed for safe fish passage, installed a high-performance Restoration Hydro Turbine (RHT), transforming the canal’s operations. The turbine generates 300kW annually, supplying central Oregon communities via the local grid.
BENEFITING COMMUNITY, INDUSTRY, AND THE ENVIRONMENT
While the Monroe Drop is a small hydro project, it stands out for the multifaceted benefits it models for hydro projects of any scale – sourcing renewable high-performance hydropower from existing infrastructure, implementing novel safe fish passage technology, and conducting ongoing field testing to advance the use of turbines designed for safe fish passage in more places around the country and throughout the world.
The project is certified as “low-impact” by the Low Impact Hydropower Institute (LIHI). Shannon Ames, Executive Director of LIHI, praised the project, stating, “Monroe is a great example of how innovative owners can operate a project consistent with power, environmental, and community needs. This project effectively and efficiently utilizes existing infrastructure to find new hydropower sources without compromising fish safety.”
Natel’s Monroe Drop project in central Oregon is certified as Low Impact by the Low Impact Hydropower Institute.
UNLOCKING ADDITIONAL CAPACITY USING CANAL FLOW
With 50GW of additional hydro required annually to limit global warming to 1.5°C, the hydro industry needs to unlock 1.2 TW additional capacity by 2050 to meet decarbonization goals. The Monroe Drop project exemplifies how conduit projects in irrigation canals, water supply lines, and other human-made structures can contribute to this goal.
These projects can bring low-impact hydropower generation to local communities nationwide, offering a reliable power source to surrounding municipalities without the need to construct new dams or diversions.
The Monroe Drop’s main canal drop structure consists of a 35-foot-long, 15-foot-high concrete open irrigation drop with concrete winged transition sections upstream and downstream.
Water falls between 13.5 feet to 16.5 feet at this structure, depending on the flow. The drop structure contains an automated gate that controls irrigation water flow, maintaining constant elevation upstream and flow downstream.
By operating passively during the irrigation season, the project relies solely on canal flow without storage, ensuring minimal ecological impact.
“Now, more than ever, it’s critical to not only maintain and upgrade existing assets but to find ways to responsibly and sustainably power the vast number of non-powered hydro resources around the country.” said Gia Schneider, CCO and co-founder of Natel. “Monroe Drop is an excellent example of a way to bring more hydropower online using existing infrastructure in a way that supports ecosystem function alongside energy production. It is possible to do both.”
The Monroe Drop is situated on an irrigation canal in central Oregon, making use of existing infrastructure to generate renewable energy with minimal impact.
HIGH-PERFORMANCE HYDRO WITH FISH IN MIND
Historically achieving safe downstream fish passage at hydropower sites has required compromise: reduce fish mortality, but lower overall energy output. However, innovations like Natel’s FishSafe™ hydro turbine designs bring new ways of minimizing ecological impact without compromising high-performance energy output.
Since 2019, Natel Energy has been developing new FishSafe™ turbine designs that achieve 98-100% survival rates across key migratory fish species while operating at high tip speeds that enable seamless integration into the constraints of existing infrastructure.
While mechanical strikes pose a significant threat to fish passing through conventional turbines, Natel’s research has shown that an altered blade design featuring a thick, slanted leading edge can dramatically improve fish survival rates—effectively reducing strike speed while maintaining greater than 90% hydraulic efficiency.
This key innovation is the basis of Natel’s family of FishSafe™ Restoration Hydro Turbine (RHT) designs. Natel works with leading turbine manufacturers to engineer RHTs for facilities of various sizes and configurations at sites up to 130 feet of head — from small projects to installations exceeding 100 MW. In the case of Monroe, Natel seamlessly replaced the previously-installed 250-kW SLH turbine with a 300kW RHT to produce more power, accommodate the canal’s unique siting needs, and enable safe fish passage.
The Monroe Drop project is home to one of Natel’s FishSafe™ Restoration Hydro Turbines (RHTs) which has been supplying reliable renewable power to the local grid since its installation in 2020.
A UNIQUE LAB FOR THE INDUSTRY
The Monroe Drop is an active fish passage testing lab and a critical piece of Natel’s research and development program, helping to validate Natel’s FishSafe turbine design while providing the broader hydro industry with data about safe fish passage.
The Monroe Drop has served as a test site for multiple through-turbine fish passage studies with Pacific Northwest National Laboratory.
The studies, conducted in 2020 and 2022 (and now pending peer-reviewed publication) passed adult rainbow trout up to 500 mm (19.7 inches) in length through the RHT with 98-100% immediate survival and no detectable injuries — indicating that the RHT allows safe passage of some of the largest fish ever successfully passed through a compact hydro turbine.
The results of these and future in-field tests provide not only Natel, but the broader hydro industry, as the meaningful results provide encouragement for owners and operators of similar sites to update their operations with turbine solutions that support renewable energy output without sacrificing broader fish and ecosystem function.
Rainbow trout and sensor fish studies conducted with Pacific Northwest National Laboratory at Natel’s Monroe Drop site have contributed to the industry’s understanding of how fish pass through Natel’s novel turbine designs.
WHAT COMES NEXT?
The Monroe Drop hydropower project showcases how innovative engineering and deliberate design can solve one of the hydro industry’s biggest challenges: producing high-performance renewable energy while maintaining healthy river ecosystems.
By leveraging existing infrastructure and serving as a laboratory for research and development of improved fish passage technology, the project models how hydro can support both energy production and environmental conservation.
As the hydro industry looks to meet future decarbonization targets, the Monroe Drop project provides an inspiring example of what can be accomplished with vision, innovation, and a commitment to sustainability.
Natel engineers and PNNL researchers recapture fish passed through the project’s RHT downstream of the plant to evaluate them after passage through Natel’s turbine designed for fish safety.
Interested in touring the Monroe Drop project before or after Clean Currents this October? Stay tuned for more information about visiting the site with Natel.
