Unsafe Dams Present Risk for Downstream Residents

Of the 90,000 or so dams in the U.S., at least 1,688 are considered high-hazard and in poor or unsatisfactory condition. Those and other dams endanger tens of thousands of lives of people who are unaware of the risk.

by Jim McKay / November 22, 2019
Two men watch as water gushes from the Oroville Dam's main spillway Wednesday, Feb. 15, 2017, in Oroville, Calif. AP

The Associated Press recently investigated the state of dams in the nation and identified 1,688 high-hazard dams rated in poor or unsatisfactory condition last year in 44 states and Puerto Rico.

he dams are considered high hazard based on the potential for loss of life if they were to fail.
States with the most high-hazard dams in poor or unsatisfactory shape included Georgia at the top with 198; North Carolina with 168; Pennsylvania with 145; Mississippi with 132; Ohio with 124; and South Carolina with 109. The data was gathered through state open records laws. More than half of the 90,000 or so dams are privately owned.

It is likely that the dams rated as unsatisfactory are receiving attention, but the dams rated poor may not be. The definition of “Poor” for the National Inventory of Dams (NID) is a deficiency of loading conditions that may realistically occur, and remedial action is necessary. The NID definition for unsatisfactory is a safety deficiency that requires immediate or emergency remedial action for problem resolution.

“I think there certainly a lot of things that are being addressed with these dams,” said Mark Ogden, a technical specialist with the Association of State Dam Safety Officials. “The ones that are in the unsatisfactory condition have been put there by the states or owners and they’re looking at something that has happened with those.”

Enforcement is time consuming and costly, and some regulatory agencies struggle to keep up because of a lack of resources.

He said that as far as the dams in the “poor” category, it’s probably not as good news. Again, it is likely that the majority of these dams are known to be in this condition, and some are being addressed, but there are several reasons why something may or may not get done.

 “Sometimes the owner understands the need and is willing to make changes but maybe doesn’t have the funding and may be working on the funding,” Ogden said. “They would be in the planning stage and I’m sure there are many of them that need repair, and the owner, for whatever reason — lack of funding or lack of acknowledgment — is doing nothing.”

The problem with that is that there are many Americans living downstream of dams in poor or unsatisfactory condition and the residents don’t realize how much danger they could be in. Many of the state regulatory agencies that have oversight over these dams are understaffed and underfunded, and there are different regulations for different states.

Alabama doesn’t have a state dam safety program at all. Some states exempt dams from regulations based on the type of dam or owner. In several states, agricultural dams are exempt from state regulatory oversight. In Missouri, a dam that is under 35 feet high, regardless of what’s downstream, is exempt. In Texas, dams that are considered in rural counties, based on population, have significant hazard potential can be exempt if a “small number” of people live downstream. There are also dams that are hidden to the public, such as those on farms, and may not be regulated.

Bob Bea, co-founder of the Center for Catastrophic Risk Management, is not optimistic about the state of dams in the country. “It’s particularly maddening to me. We are a very blessed country, and yet over the last several years there’s a repeated litany of miserable experiences,” he said.
He said the formula is “Watching it failing, watch it fail, fix it fast, return to business as usual.” Oftentimes, he said, the fix doesn’t necessarily mean the dam is safe.

Of the breach of California’s Oroville Dam in 2017, Bea said that a failure of that dam, with some 200,000 people residing below it, would be more catastrophic than Hurricane Katrina’s aftermath. And how many other Oroville Dams are there across the country? Maybe 2,000, he said.

“The first thing we have to do is admit we’ve got an important problem that challenges the welfare of thousands of people in the United States,” Bea said. “Our long-term welfare is challenged.”

He said it’s a case of there being 90,000 dams, more than half of which are privately owned and many of which are in poor or unsatisfactory condition, and not enough people who can truly define what is safe and what is unsafe. And officials can be overwhelmed because of the expense and magnitude of fixing these dams.

“We would sit down with [state] leaders and their staffs and explain what we’d learned. We got polite reception, they asked good questions and then we’d leave and there was silence.”

Definitions, as accepted by the National Dam Safety Review Board, are as follows:

1. SATISFACTORY No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the applicable regulatory criteria or tolerable risk guidelines.

2. FAIR No existing dam safety deficiencies are recognized for normal loading conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.

3. POOR A dam safety deficiency is recognized for loading conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters that identify a potential dam safety deficiency. Further investigations and studies are necessary.

4. UNSATISFACTORY A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.

5. NOT RATED The dam has not been inspected, is not under state jurisdiction, or has been inspected but, for whatever reason, has not been rated.

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