Aging large dams are an emerging global risk as tens of thousands of existing structures have reached or exceeded an “alert” age threshold of 50 years, with many others soon approaching 100 years, according to a new report from the United Nations University’s Institute for Water, Environment, and Health. It observes that older structures incur rapidly rising maintenance needs and pose potential threats to human safety and the environment. And despite plans in some regions and countries to build more water storage dams, there will not be another “dam revolution” to match the scale of the high-intensity dam construction experienced in the early to middle 20th century. At the same time, many of the large dams constructed then are aging, hence a “mass aging” of water storage infrastructure. The report shows that while dam decommissioning is a relatively recent phenomenon, it is gaining pace in some places, including in the U.S., where many dams are older. However, it is primarily small dams that have been removed to date, and the decommissioning of large dams is still in its infancy, with only a few known cases in the last decade. A few case studies of aging and decommissioned large dams illustrate the complexity and length of the process that is often necessary to orchestrate the dam removal safely. Access the report at the United Nations University’s Institute for Water, Environment, and Health.