New Study: US Hydropower Threatened by Increasing Droughts Due to Climate Change

Montana, Nevada, Texas, Arizona, California, Arkansas and Oklahoma expected to be most impacted.

A new study published in the journal Water assesses the risks of floods and water scarcity to hydropower projects and how those risks may shift due to climate change. Several regions of the United States with hydropower are among those where river basins are projected to have the greatest increase in risk of water scarcity by 2050. Future droughts could potentially create challenges for hydropower projects, especially in Montana, Nevada, Texas, Arizona, California, Arkansas and Oklahoma.

The study finds that by 2050, 61 percent of all global hydropower dams will be in basins with very high or extreme risk for droughts, floods or both. By 2050, 1 in 5 existing hydropower dams will be in high flood risk areas because of climate change, up from 1 in 25 today. Only 2 percent of planned dams are in basins that currently have the highest level of flood risk, but by 2050, nearly 40 percent of this same group of dams will be in basins with the highest flood risk.

“Hydropower projects must deal with a range of hydrological risks–ranging from too little water to too much–and these risks are projected to increase in many regions due to climate change,” says WWF’s Global Freshwater Lead Scientist, Jeff Opperman. “Already, we’ve seen regions, such as the southwestern US, southern Africa, and Brazil, where hydropower generation has declined due to falling water levels.”

Biodiversity is also at risk from hydropower dam development. Freshwater species populations have declined by an average of 84 percent since 1970. Hydropower dams are cited as a leading cause of this decline, yet up to 80 percent of all planned dams are in areas with high or very high risk to biodiversity.

“Too often, hydropower dams were built in places that resulted in major negative impacts to rivers and their resources, such as the fisheries people depend on for food and recreation,” says Opperman. “For decades, hydropower was the cheapest option for low-carbon and renewable energy generation, but the cost of wind and solar have dropped so quickly and so far, that in most of the world they have become the cheapest form of electricity available. So countries now have more choices. With the need to dramatically accelerate the development of low-carbon energy generation projects, countries should find energy development pathways that are low carbon, low cost and minimize impacts on nature and people - and vulnerability to climate change needs to be an important part of that planning.”

Just last year, heavy rainfall caused two Michigan dams to collapse. Thousands of people had to evacuate. U.S. government and industry leaders are making efforts to manage the energy grid more sustainably. The American Society of Civil Engineers recently released a report card that grades different types of infrastructure in the US, and they gave dams a “D,” citing 16,000 aging dams across the U.S. in need of repair. The recently enacted Bipartisan Infrastructure Law includes an $800 million investment in the removal of risky dams, which will help restore free-flowing rivers, along with another $1.6 billion aimed at improving dam safety and investing in improvements to existing hydropower, including raising their environmental performance and resiliency to climate change.

The study used a publicly available tool called WWF’s Water Risk Filter to assess high-risk basins where dam projects are located or planned. Healthy rivers support freshwater fish stocks that improve food security for hundreds of millions of people, deliver sediment that keeps deltas above rising seas, mitigate the impact of extreme floods and droughts, prevent loss of infrastructure and fields to erosion, and support a wealth of biodiversity.



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About WWF Water Risk Filter

Launched in 2012, the WWF Water Risk Filter ( was one of the first online water risk assessment tools designed for companies and investors to assess water risks in their operations, supply chains and investments, in a spatially explicit manner and at the global scale. With the latest tool upgrade in 2021, users are now able to perform forward-looking scenario analysis to evaluate how water risks may evolve over a 10- and 30-year time frame (2030 and 2050) under different climate and socio-economic scenario pathways. By better assessing current and future water risks, companies and investors can prioritize action where it matters the most to address water risks for enhancing business resilience and contributing to a sustainable future.