CEAC-2022-06-June

community associations, state and local governments, and
other entities besides the federal government, according to a
report by the Association of State Dam Safety Officials.
The U.S. Army Corps of Engineers lists about 92,000 dams in
its nationwide database, most of which are privately owned
and regulated by states. Dams are classified according to the
risk posed by failure, ranging from low to significant to high.
A high hazard means lives could be lost if the dam fails.
Dams also are assessed by their condition. Those in the worst
shape — categorized as poor or unsatisfactory — can have a
variety of problems including cracks and erosion that could
undermine a dam, or spillway outlets unable to release all
the water after extraordinary rainfall.
The number of high-hazard dams in poor or unsatisfactory
condition has risen partly because of stricter regulation.
Some state programs, infused with millions of additional
dollars, have stepped up inspections, reassessed whether old
dams endanger new downstream developments and worked
to identify dams long ago abandoned by their owners. Some
also are updating the precipitation tools used to evaluate
the risks.
New York has about twice the number of high-hazard dams
in poor condition as it did in 2018, when the AP collected
data for its earlier analysis. The increase came as officials
pushed to assess all high-hazard dams that were previously
unrated.
The number of high-hazard dams in deficient condition
in South Carolina rose by a third from 2018 to 2021, after
lawmakers more than doubled annual funding for the
state’s dam safety program. More than 70 dams failed in the
state amid heavy rains in 2015 and 2016. Since then, South
Carolina has ramped up staffing, undertaken more regular
inspections and begun mapping potential flood zones for
low-hazard dams to determine if they should be reclassified
as high hazard.
“When you had a storm of that magnitude and you have it
happen again the next year, and dams continue to fail, we’ve
got to be able to provide a response,” said Jill Stewart, the
state’s director of dam safety and stormwater permitting.
Rhode Island examined the capacity of all its dam spillways
after five dams failed during a storm in 2010. A 2019 study
found that a quarter of its high-hazard dams couldn’t hold
up to a 100-year storm — an event with a 1-percent chance
of happening any year — and 17 percent couldn’t pass a 500-
year storm, which has a 0.2-percent chance of occurring in a
year.
The state was sharing the findings with dam owners and
could require some to upgrade their spillways to meet state
regulations.
Many old dams “are undersized for the kind of storms that
we’re getting today and will be getting in the future,” said
David Chopy, administrator of the Office of Compliance and
Inspection at the Rhode Island Department of Environmental
Management.
Since 2019, California regulators have downgraded four of
San Diego’s water supply dams from fair to poor condition
because of deterioration and concerns they could fail because
of an earthquake or extraordinary rainfall. As a result,
the high-hazard dams at El Capitan, Hodges and Morena
reservoirs all are restricted to holding less than half their capacities.
The dam at Lower Otay Reservoir, also high hazard
(Continued on pg. 14)
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