From The New York Times (Troy Griggs, Gregor Aisch and Sarah Almukhtar):
Nearly 2,000 state-regulated high-hazard dams in the United States were listed as being in need of repair in 2015, according to the Association of State Dam Safety Officials. A dam is considered “high hazard” based on the potential for the loss of life as a result of failure.
By 2020, 70 percent of the dams in the United States will be more than 50 years old, according to the American Society of Civil Engineers.
“It’s not like an expiration date for your milk, but the components that make up that dam do have a lifespan.” said Mark Ogden, a project manager with the Association of State Dam Safety Officials…
Two weeks ago, heavy rains caused the Twentyone Mile Dam in Nevada to burst, resulting in flooding, damaged property and closed roads throughout the region.
The earthen dam, built in the early 1900s and less than 50 feet tall, is one of more than 60,000 “low hazard” dams, according to the Army Corps of Engineers. Typically, failure of a low hazard dam would cause property damage, but it would most likely not kill anyone.
In 2016, the Association of State Dam Safety Officials estimated that it would cost $60 billion to rehabilitate all the dams that needed to be brought up to safe condition, with nearly $20 billion of that sum going toward repair of dams with a high potential for hazard.
In 2015, Representative Sean Patrick Maloney, Democrat of New York, introduced the Dam Rehabilitation and Repair Act, an amendment to the National Dam Safety Program Act, to provide grant assistance to rehabilitate publicly owned dams that fail to meet minimum safety standards.
The bill is still pending, but it would not apply to a majority of the dams in the United States because more than half of them are privately owned. Oroville Dam is owned by the State of California, but the Twentyone Mile Dam is owned by Winecup Gamble Ranch, a cattle operation in northeastern Nevada.
While most legislation involves inspection and rehabilitation, hazardous dams that have outlived their usefulness can also be removed.