Dams are aging across the USA
1 in 5 facilities in growing populated areas don’t have ‘a good emergency action plan’
Communities downstream increasingly at risk
As the nation’s 84,000 dams continue to age, a growing number of people downstream are at risk, experts say.
That’s not only because of older infrastructure but also because of population growth around some of the dams.
More than a quarter were developed primarily for recreational purposes, according to National Inventory of Dams data from 2016.
“The nation’s dams are aging, and the number of high-hazard dams is on the rise,” according to a report in 2013 from the American Society of Civil Engineers. “Many of these dams were built as low-hazard dams protecting undeveloped agricultural land. However, with an increasing population and greater development below dams, the overall number of high-hazard dams continues to increase.”
That problem was highlighted this week as nearly 200,000 people evacuated an area near Cali- fornia’s Oroville Dam, about 150 miles northeast of San Francisco. California water officials were worried that erosion they discovered Sunday at the top of its emergency spillway could send a 30-foot-tall wall of water down the Feather River and through the Northern California cities of Oroville, Yuba City and Marysville.
The population of Oroville, less than 10 miles downriver from Oroville Dam, has more than doubled since the dam was completed in 1968.
Most U.S. dams were completed from 1950 to 1980. A small fraction of dams, 2.8%, were built before 1900. More than 4,000 dams have been built since 2000, accounting for 4.5% of all U.S. dams.
The latest data in the dams inventory, which the Army Corps of Engineers compiles, show almost 15,500 dams across the USA are characterized as high hazard, meaning at least one person could die if the dam were to fail.
“The nation’s dams are aging, and the number of high-hazard dams is on the rise,” according to the report. “Many of these dams were built as low-hazard dams protecting undeveloped agricultural land. However, with an increasing population and greater development below dams, the overall number of high-hazard dams continues to increase.”
Among those high-hazard dams, nearly one in five lack an emergency action plan, a document dam owners maintain that includes critical information such as emergency contacts, details about the dam and an inundation map.
“If you have a good emergency action plan, you are going to re- duce the consequences if the dam fails,” said Lori Spragens, executive director of the Association of State Dam Safety Officials.
The average age of the USA’s 84,000 dams is 52, according to the American Society of Civil Engineers’ report.
“We can’t seem to get the federal government or the states interested in funding the most fundamental part of what makes us go, which is infrastructure,” Spragens said. “It just needs so much more attention at a national level.”
In seven states, more than half of the high-hazard dams operate without emergency action plans, according to the National Inventory of Dams: In South Carolina, it’s 96%. Mississippi, 88%. Rhode Island, 82%. Alabama, 79%. New Mexico, 61%. Florida, 58%.
North Carolina, 57%. Only three states — Louisiana, Maine and Tennessee — and Puerto Rico have emergency plans in place for all the dams with high-hazard potential.
California has more than 1,500 dams, according to the National Inventory of Dams database. Of those, 52% are high-hazard, the fourth-highest of any state.
Nationwide, 17% of dams are high-hazard.
In California, more than a third, 36%, of the high-hazard dams don’t have an emergency plan, which would kick into gear if the dam appeared to be a threat.
Oroville Dam does have an emergency plan.
A building is submerged in flowing water at Riverbend Park as the Oroville Dam releases water Monday.