Last week, heavy rainfall caused a dam to collapse in Michigan, which led to the downstream breach of a second dam and in turn catastrophically flooded communities in the central part of the state. As flood levels surged to as much as nine feet in some areas, about 10,000 residents evacuated the city of Midland, and Michigan Governor Gretchen Whitmer declared a state of emergency.
For further context on the maintenance, regulation, and economics of dams nationwide, RFF Senior Fellow Margaret Walls shares her expertise. Walls and colleagues at Resources for the Future will, in the coming months, publish research results focused on the benefits and costs of dam removal, particularly as an option for old and failing dams that no longer serve a valuable purpose.
Resources: Do the dam breaches in Michigan bear any lessons for dam maintenance that should be applied to the tens of thousands of dams across the United States?
Margaret Walls: I think it is a warning call, as these things often are when they happen.
Dam breaches are not common, but they do happen from time to time, and they bring to the public’s attention that we have a lot of aging, old infrastructure that is in need of some very costly repairs—or, in some cases, removal altogether.
I think the lesson is that it's very hard. You have to have regulations in place, you have to enforce the regulations, and the owners of these dams have to have the money for necessary repairs to prevent these kinds of things from happening.
Can you explain who bears the primary responsibility of maintaining the safety and integrity of dams across the country?
First of all, people need to understand that dams serve a variety of purposes. These two dams were originally hydropower dams, but hydropower dams are a small proportion of all the dams in the country. There are dams for water storage, flood control, recreation, and other purposes. And there are many old dams that no longer really serve any purpose at all.
The Federal Energy Regulatory Commission (FERC) is responsible for all the hydropower dams. In this case, FERC was originally in charge of regulating both of the dams that failed, because the dams were producing hydropower, but there were a number of problems over the years with the Edenville Dam—the upstream structure that collapsed. Eventually, FERC revoked the license that the Edenville Dam operated under, and the responsibility for regulating the safety of the dam fell to the state of Michigan and its dam safety office.
A few other federal agencies are responsible for other federally owned dams, such as the Bureau of Reclamation in the West and the Army Corps of Engineers, but primarily, state agencies are responsible for regulating most dams and ensuring safety.
What funding is available for dam maintenance or removal? What happens—or should happen—if funding is unavailable?
The short answer is: not very much funding is available.
In general, the responsibility for maintenance or removal lies with the owner of the dam—and most dams are privately owned, though many are owned by local governments. But of course, sometimes these costs become astronomical.
A few states are really proactive and doing a better job with making funding available. Massachusetts has the Dam and Seawall Repair or Removal Program, which is a grant program to pay for both removals and repairs of municipally owned dams. But there are very few of these kinds of programs around. The Federal Emergency Management Agency (FEMA) runs the Rehabilitation of High Hazard Potential Dams Grant Program. It was authorized up to $10 million this year, but there has only been one round of funding, and $10 million is a drop in the bucket, to be honest.
The FEMA program is geared toward high-hazard dams. The way that safety regulations tend to work is they give dams a safety rating called high, significant, or low hazard. These ratings don't say anything about the likelihood of the dam failing; they just estimate the damages if a dam were to breach and flood downstream, as these Michigan dams did. The high-hazard dam rating assumes that if a failure occurs, there is a likelihood of at least one death.
Most dams are not high hazard, but a significant proportion are: 15,491 dams—nearly 17 percent—of the 91,457 dams listed in the Army Corps of Engineers’ National Inventory of Dams. Both the Edenville and Sanford Dams in Michigan were rated as high-hazard dams. The number of high-hazard dams should be expected to increase as more development occurs downstream of dams, and as states change their flood modeling to account for increasing numbers of “probable maximum floods.”
Finally, the Edenville Dam had an “unsatisfactory” condition rating. That’s the lowest of four condition ratings a dam can get and means that the dam has a deficiency that requires “immediate or emergency action.”
In the coming months, you will release some research results related to dam removals. Can you talk about how the possibility of removal relates to dam safety?
This project, which I'm doing with colleagues Leonard Shabman and Vincent Gonzales, is mainly looking at how dam owners are incentivized to consider the option of removing a dam. We look at how state dam safety programs interact with dam owners; how the dam safety programs work together with fish and wildlife agencies and environmental agencies on water quality and river restoration issues; and how those agencies, along with the NGO community, work to spur at least consideration of dam removal.
Why are we talking about removing dams? In addition to a lot of these dams no longer serving a useful purpose and perhaps being safety hazards, dams really alter the river system and create a number of ecological problems. The most notable that people are concerned with is fish passage. This is a huge issue in the Pacific Northwest and in the Chesapeake Bay region, where spawning fish can't make their way back and forth between the ocean and streams because of the barriers created by dams.
In many cases, when dam owners are actually faced with a choice to invest in very costly repairs, dam removal often is the more cost-effective option. That's not always the case—and sometimes the dam, or the reservoir that it's created, has value—but in many cases, that value just isn’t enough, and the maintenance costs are so high that removal is a better option.
Nonetheless, if they don't have the money, then a dam is just not going to get repaired or removed.
Can you speak to the choice that dam owners need to make, in terms of balancing the protection of human communities and the protection of ecological systems?
The way an economist would do this is by asking: What are the social benefits? What are the social costs? Let's find the optimum, and let's figure out what policy instrument to put in place.
A policy instrument can regulate the owner to do certain things. Or it could use more of a financial incentive approach. But let's figure out how to do it to maximize the net social benefits, which would include fish passage, ecological health, the recreation benefits of a reservoir, and all the associated costs.
Unfortunately, we're in a world where none of that is really being done. It is difficult, and each dam is a little bit different.
The solutions are absolutely not straightforward. We are not saying that a lot of dams need to come out. What we're really saying is that, right now, the decision about whether a dam should come out is not even being made in a systematic way.