Old dams need attention as potential historic properties
Recent flooding events in California have brought attention to the need to repair or replace many older dams in the U.S. An article, “America’s Aging Dams Are in Need of Repair,” in The New York Times noted the deteriorated condition of thousands of dams nationwide.
As a preservation professional, I was struck by the detail that the average age of over 90,500 dams in the country is now 56 years old. By 2025 fully 70 percent of these dams will be more than 50 years old, according to the American Society of Civil Engineers. This exceeds the minimum age requirement for consideration as a historic property.
This means that qualifying old dams will need to be treated as historic properties if work is planned using federal funds, or needs a federal permit. The magnitude of this challenge calls not only for a substantial financial commitment (yet to be identified by dam owners who are primarily government entities), but also necessitates a thoughtful approach to design and construction solutions.
ASCE provides data to support the need for improvements to dams. In the Report Card for America’s Infrastructure, dams receive a grade of D+ based on their overall condition. ASCE estimates that $3.6 trillion would be needed to fully address needed improvements. Deterioration of dam elements and inadequate capacity are of significant concern when infrastructure receives this poor grade.
Old dams are part of a “baby boom for National Register eligibility.” This boom was forecast ten years ago by the National Park Service, the federal agency responsible for historic preservation programs, when noting the surge in public buildings reaching 50 years of age, the minimum age requirement to be considered historic. However, age is not sufficient to warrant National Register of Historic Places eligibility; to be considered “historic” a property must also possess a high degree of physical integrity and demonstrate historical significance within the appropriate context. Many of our clients’ dams are over 50 years old, and in some cases more than 100 years old. We often need to take into consideration whether the structures are historically significant when making repairs or alterations for reasons associated with dam safety.
Repairs that result in preservation of historically significant dams have broad economic and cultural benefits. Tom Mayes of the National Trust for Historic Places described the role and value of historic places in an article on the National Historic Preservation Act turning 50 years old: “we can use our older assets to foster a strong economy; recognize the histories of all Americans; extend the benefits of preservation to all people; learn at historic places; promote the tourism that sustains many of our historic towns and enlarges our minds; and maintain the beauty of old places that enhance our communities.”
The convergence of dams aging and their potential recognition as historic properties does not need to be cataclysmic. With thoughtful planning and careful execution, I’m confident that certain historic dams can be restored to a good and safe condition that allows them to function well into the future and to be upheld as important examples of engineering heritage.
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