The claim that hydropower is environmentally unsustainable is misleading. Hydropower is one of the most sustainable and low-carbon sources of energy available today, especially when compared to fossil fuels.Hydropower emits, on average, about 13 grams of CO2 equivalent per kilowatt-hour (g CO2-eq/kWh) over its entire lifecycle. This includes emissions from dam construction, operation, and maintenance. By contrast, fossil fuels like natural gas and coal emit 486 g CO2-eq/kWh and 1,001 g CO2-eq/kWh, respectively, according to data from the National Renewable Energy Laboratory.(1) This means that hydropower generates only about 1/77th the emissions of coal over its lifecycle, making it far more environmentally sustainable.(1)While it’s true that large-scale hydropower projects can have environmental impacts, particularly related to aquatic ecosystems, modern hydropower plants have increasingly incorporated technology, environmental management and mitigation strategies to reduce ecological footprint. These include fish ladders to help species migrate, better water management practices, and the use of smaller, run-of-river hydro systems that minimize the need for large reservoirs.(2)