The Army Corps of Engineers grades the U.S. dam infrastructure a “D” and estimates it will take $45 billion to fix our aging, high-hazard dams.
Dam failures are a
low probability but
event, best addressed
by preparation and
By Juliann Walsh
After a five-year drought, the rains finally returned to California this winter. Lake Oroville, which was formed in 1967 at the foot of the Sierra Mountains by the nation’s tallest dam, began to refill. An atmospheric river, colloquially known as a “Pineapple Express,” continued dropping water at such a pace that it replenished the
reservoir and then some. The swollen lake forced the excess water onto an
emergency spillway alongside the Oroville Dam for the first time in half a century.
The spillway cement crumbled and sent a cascade of water down the
mountainside. Engineers feared the erosion compromised not only the spillway
but also the 770-foot-tall earthen dam.
An emergency evacuation was hastily ordered and nearly 190,000 residents
were forced to flee their homes. Traffic clogged roads. Fortunately, no life was lost
and water levels eventually receded.
For many, this crisis is a wake-up call for renewed assessment of the aging
infrastructure of the U.S. dam system and the emergency response plans drawn to
prevent loss of life in the event of a failure.
DAMS EXCEEDING EFFECTIVE DATES
Nearly all of the 700 dams managed by the U.S. Army Corps of Engineers
are more than 30 years old. More than half have reached or exceeded the 50-year
service lives for which they were designed. Oroville Dam turns 50 next year.
Tim McCarty is a risk control manager at Trident Public Risk Solutions, which
insures a wide range of municipalities including those in close proximity to a dam.
His statistics on the aging dam system in the U.S. are alarming.
“The average age of our dams nationwide is 56 years,” he said. “And the
average age of a failed dam is 62 years. “So we’re kind of reaching that point
where we’re starting to have some very old infrastructure and if it’s not properly
maintained we may see repeats of this type of an incidence,” McCarty said.
The Federal Emergency Management Agency says dam failures are a “low
probability but high consequence” event. Due to the rarity, many people who live
downstream in “dam breach inundation zones” are completely unaware of the
potential hazard. But they are, in fact, at the mercy of the dam’s ongoing health.
“The only time the concept is front and center is when water is rushing over
the dam,” said John Dickson, president of NFS Edge Insurance Agency.
“I worry constantly that that’s a total disservice to the American people. We
need to have the conversation when the sun is shining.”
Dams are a vital part of the U.S. infrastructure. They provide flood protection,
water supply, hydropower, irrigation and recreation. But all it takes is one busy
muskrat to compromise a dam’s integrity and cause a breach.
The operators of the Oroville Dam were advised in 2005 to shore up the
spillway with concrete. For a dozen years, the expensive recommendation was
tabled. The reasoning was the emergency spillway was never used because the lake
water never rose high enough.
When it finally did, the emergency response — mass evacuations and
helicopters dropping dirt and boulders to fortify the dam — averted a
catastrophe. But it was an expense way beyond the cost of maintenance. And some
never received notice of the evacution, according to the Associated Press.
DAMS FAIL QUICKLY
Every four years, the American
Society of Civil Engineers issues
a “Report Card for America’s
Infrastructure.” Bridges, roads, and
tunnel systems are evaluated on
capacity, condition, funding, future
need, operation and maintenance,
public safety, resilience and innovation.
“The average age of our dams
nationwide is 56 years. And the
average age of a failed dam is
—Tim McCarty, risk control manager, Trident
Public Risk Solutions
• The U.S. dam infrastructure is
aging and needs repair.
• Dam breaches are rare but can
be significant events
• A 2017 report rates U.S. dam
infrastructure a “D.”