In a rapidly evolving landscape of climate change, growing populations, and environmental awareness, water management is facing unprecedented challenges in many regions. A new commentary from researchers at the USGS and the U.S. Forest Service sheds light on the complex web of issues surrounding dam and reservoir management in the 21st century. 

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The era of large dam construction, which peaked in the U.S. six decades ago, is now giving way to an evolved paradigm. Climate change, population growth, reservoir sedimentation, aging dams, and evolving environmental priorities are reshaping the narrative of dam management. The commentary highlights the pressing need for innovative solutions to navigate this intricate matrix of challenges. 

"The way we perceive dams and reservoirs has changed in recent decades. The challenges we face today are multifaceted and demand a holistic approach," said USGS Research Geologist Amy East, lead author of the summary.  

A prominent example is the Colorado River’s Glen Canyon Dam, which turned 60 years old in 2023. Storage in the reservoir it impounds, Lake Powell, was lower than at any time since the reservoir first filled, and environmental impacts have become apparent downstream of the dam that were not anticipated when the dam was built. Complex efforts to mitigate environmental impacts, including by modifying dam operations, are under way in many watersheds, including the Colorado River.  

The commentary also notes the rising trend of dam removal as a response to safety concerns, obsolescence due to excessive sedimentation, and economic inefficiency. Dam removal has increasingly become a common tool to manage reservoirs and downstream habitats. This trend is particularly pronounced where dams are deemed unsafe or uneconomical beyond salvage. 

"Dam removal is not merely a reactive measure; it's a strategic response to changing conditions. It's about adapting to a dynamic environment and reimagining the role of rivers in our landscapes," said U.S. Forest Service Research Hydrologist Gordon Grant, co-author of the summary. 

The science and practice of dam removal are evolving at a rapid pace, driven by the urgency of the challenges at hand. Some long-term studies on the physical and biological responses to dam removal are now available, offering valuable insights into the recovery processes of ecosystems and river dynamics. 

"The ways in which society’s views on dams—managing them and knowing when to remove them—have changed in recent decades reinforce the importance of careful, science-based decision-making in managing our water resources," said East. 

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