Most dams and locks do not generate electricity, but some can be retrofitted for hydropower.
Costs, power generation capacity, and environmental impacts affect which dams are retrofitted.
An online toolkit can identify the best non-powered dam (NPD) candidates to generate hydropower.
Dams are built on rivers to block or control the flow of water, and can also include locks to regulate water elevation. Dams can generate electricity from the flow of water, known as hydropower. Hydropower is a renewable source of energy with low greenhouse gas emissions, and provides 6% of electricity in the U.S. (Office of Energy Efficiency and Renewable Energy n.d.). The total capacity of hydropower generation in the U.S. is approximately 80 gigawatts (GW) (Department of Energy (DOE) 2018).
There are over 92,000 dams in the U.S., of which 2,500, or 3%, generate electricity (Army Corps of Engineers n.d.). Adding electricity generation capabilities to all currently non-powered dams and locks (NPDs) would increase the U.S.’s hydropower capacity by an estimated 12 GW, or 15% (Hadjerioua 2012). Retrofitting a NPD also removes the cost of building a new dam (Bevan 2021). For more information, see our Science Notes on Hydropower and Small Scale Hydropower.
Because NPDs were not originally designed for hydropower generation, many are not viable options for retrofitting. Several major considerations contribute to evaluating NPD retrofit development (DeNeale et al 2022a, Oladosu et al. 2021). Adding hydroelectric capabilities may interfere with the dam’s original function. The dam may be far from power lines and would require more construction to connect it to the grid. Retrofitting a dam for hydropower may change the flow of water and damage the surrounding ecosystem.
For these reasons, 120 of 156 retrofit projects proposed between 2000 and 2020 did not become operational (Hansen et al. 2021). Of the unsuccessful proposals, 109 received a permit from the Federal Energy Regulatory Commission (FERC) to study the project’s feasibility. Out of these permitted projects, 107 ended before applying for a FERC license to begin construction. These proposals ended either due to a lack of progress or when the developer voluntarily surrendered their permit. Retrofitting projects commonly end when the costs of adding electrical generation exceed the revenue and other benefits from the added power (Bevan 2021, Hansen et al. 2021).
Pairing a retrofitting project with another energy project (such as storage, transmission, or additional generation) can lower the costs of both (DeNeale et al. 2022a, Andrade Furtado et al. 2020). Development of less expensive materials and more efficient turbines also improves economic feasibility of retrofitting NPDs (Oladosu et al. 2021).
Most NPDs that have been retrofitted for hydropower are federally operated by the U.S. Army Corps of Engineers (DeNeale et al. 2022b). Locks and dams on the Ohio River account for 74% of all NPD retrofitting projects between 2006 and 2016 (Hansen et al. 2021, Energy Information Association 2016). Most recently, in 2025, the Robert C. Byrd Locks and Dam in West Virginia obtained FERC approval to construct a 28.5 megawatt (MW) hydroelectric facility (Current Hydro 2025). On the Mississippi River, the locks and dam in Marion County, MO, and Adams County, IL have received a FERC permit to study feasibility of a 15 MW hydropower retrofitting project and plan to apply for a construction license in 2027 (Skelly 2026, Reese 2024).
To evaluate the feasibility of retrofitting NPDs for hydropower, researchers created the NPD HYDRO Toolkit (Idaho National Laboratory (INL) 2023). The toolkit contains a database with information on 2616 NPDs in the contiguous U.S., including 47 in MO (Figure 1). It also ranks candidate NPDs for retrofitting based on community and environmental impacts, benefits to local industry, and proximity to grid infrastructure.
Figure 1. Locations of non-powered dams (NPDs) in Missouri. Each dot color corresponds to a different type of owner. These NPDs do not generate electricity but could potentially be retrofitted for hydropower generation. Figure adapted from Idaho National Laboratory and Pacfic Northwest National Laboratory’s NPD HYDRO Toolkit (INL 2023).
References:
Andrade Furtado CGd, Amarante Mesquita AL, Morabito A, Hendrick P, Hunt JD (2020) Using hydropower waterway locks for energy storage and renewable energies integration. Applied Energy. 275: 115361. https://doi.org/10.1016/j.apenergy.2020.115361
Bevan C (2021) “Dammed if you don’t” Industry perspectives on regulatory obstacles to an policy incentives for the electrification of non-powered federal dams in the United States. National Hydropower Association. https://www.hydro.org/wp-content/uploads/2021/04/3.30-Final-NHA-Paper_Connor-Bevan.pdf
Current Hydro (n.d.) Robert C. Byrd Hydroelectric Project. https://www.currenthydro.com/rc-byrd
DeNeale S, Sasthav C, Musa M, Hansen C, Stewart K, et al. (2022) Non-Powered Dam Retrofit Exemplary Design for Hydropower Applications. Oak Ridge National Laboratory. https://info.ornl.gov/sites/publications/Files/Pub167488.pdf
DeNeale S, Hansen C, Feyyisa J, Oladosu G (2022) An assessment of non-powered dam hydropower development opportunities in the United States. Oak Ridge National Laboratory. https://info.ornl.gov/sites/publications/Files/Pub177385.pdf
Hadjerioua B, Wei Y, Kao S-C (2012) An Assessment of Energy Potential at Non-Powered Dams in the United States. Oak Ridge National Laboratory. https://www1.eere.energy.gov/water/pdfs/npd_report.pdf
Hansen C, Musa M, Sasthav C, DeNeale S (2021) Hydropower development potential at non-powered dams: Data needs and research gaps. Renewable and sustainable Energy Reviews. 145: 111058. https://doi.org/10.1016/j.rser.2021.111058
Idaho National Laboratory (INL) (n.d.) NPD HYDRO Toolkit. https://npd-hydro.inl.gov/
International Commission on Large Dams (n.d.) Role of dams. https://www.icold-cigb.org/article/GB/dams/dams/role-of-dams
Oladosu G, George L, Wells J (2021) 2020 Cost Analysis of Hydropower Options at Non-Powered Dams. Oak Ridge National Laboratory. https://info.ornl.gov/sites/publications/Files/Pub145012.pdf
Reese D-A A (2024) Low Head Hydro M 21, LLC; Notice of Preliminary Permit Application Accepted for Filing and Soliciting Comments, Motions To Intervene, and Competing Applications. Federal Register. 2024-23744 (89 FR 82998). https://www.federalregister.gov/d/2024-23744
Skelly AW (2026) 1st Annual Report to the Federal Energy Regulatory Commission: Proposed Hydropower Project – Mississippi Lock and Dam 21, Quincy, Illinois. Federal Energy Regulatory Commission eLibrary. https://elibrary.ferc.gov/eLibrary/filelist?accession_number=20251230-5171
U.S. Army Corps of Engineers (n.d.) National Inventory of Dams. https://nid.sec.usace.army.mil/nid/#/
U.S. Department of Energy (DOE) (2018) Hydropower Vision: A New Chapter for America’s 1st Renewable Electricity Source. https://www.energy.gov/eere/water/articles/hydropower-vision-report-full-report
U.S. Department of Energy Office of Energy Efficiency and Renewable Energy (n.d.) Hydropower basics. https://www.energy.gov/eere/water/hydropower-basics
U.S. Energy Information Association (2016) Several nonpowered dams along the Ohio River to be converted to hydroelectric dams in 2016. https://www.eia.gov/todayinenergy/detail.php?id=27092
