The Consequence of Doing Nothing
Improving Dam and Levee Safety Awareness Requires Understanding Risks and Consequences
Let’s say you hear a funny noise from your car while driving down the road. You have two options: Turn up the radio and proceed onward, or find a safe place to pull over and investigate. It’s definitely worth checking out, because your car could be sending you a signal that something is not right, and the potential consequence could be a minor inconvenience or a life-threatening mechanical failure.
There is a lot of noise in the dam and levee industry that can distract a dam or levee owner. Competing priorities, financing challenges, regulatory requirements and environmental concerns all make it difficult to prioritize safety improvements over other needs. Knowing the condition of our dams and levee structures is now more vital than ever. As downstream development continues, the magnitude of consequences continues to increase. Long-term water supply can be lost, lives may be threatened, and there could be significant damage to the built and natural environment should an incident occur. To mark National Dam Safety Awareness Day, we caught up with our experts Bob Beduhn, Dan Osmun, Leslie Tice and Chris Behr to capture their thoughts on the importance of addressing our nation’s aging dams and levee structures, the consequences if we fail to take action, and the types of innovative solutions we can employ for the future.
A recent report from the Association of State Dam Safety Officials has documented the rising cost burden of rehabilitating high hazard dams due to a combination of worsening conditions. How are dam owners and operators responding?
Behr: Dam owners face significant constraints in knowing how to prioritize and pay for improvements in safety. Currently, the average age of dams in the U.S. is 61 years. According to ASDSO, 73% of our nation’s dams will be more than 50 years old by 2025. Not only do older dams need increasing levels of normal maintenance, but new threats and safety requirements are likely to arise due to the greater frequency in extreme events. Moreover, some dams that are upstream from growing urban areas face increased consequences of failure, and this in turn has changed their classification from an original design to a high hazard dam and led to higher costs to meet those more stringent safety standards. While advances in scientific knowledge can help owners and operators identify ways to meet dam safety standards, the availability of funds is limited. Avoiding issues is not an effective strategy as deferred maintenance only becomes more expensive.
Owners and operators are trying to do more with less and at the same time seek additional outside support. Federal and state programs have answered this call with significant increases in funding, especially for high hazard dams. The Federal Emergency Management Agency’s National Dam Safety Program has allocated hundreds of millions of dollars in additional funding. In addition, the Department of Agriculture’s Natural Resources Conservation Service offers grants for dam rehabilitation through its Watershed Rehabilitation Program. Also, the U.S. Army Corps of Engineers’ relatively new Water Infrastructure Financing Program provides low-interest loans to dam owners for rehabilitation projects. However, considering that ASDSO estimates the rehabilitation of just the most critical dams to cost over $30 billion, more funds and new solutions are critically necessary.
What happens when dams or levees are past their useful life and can no longer be modified?
Beduhn: There is a two-part answer to this question. If there is still need for the dam’s purpose, such as flood control, water supply or power generation, the approach has been to consider a new replacement dam that meets modern dam safety and environmental requirements. However, there is an increasing awareness that the dam may no longer be serving a beneficial purpose. Today, we are seeing increasing interest in dam removal to restore the natural floodplain and free-flowing river systems.
Osmun: On the contrary, with proper and timely maintenance over time, owners could avoid having their dams and levees get to the point where they can no longer be modified. For some structures, the answer is to do what is necessary to avoid getting to that point in the first place.
How does a potential dam removal affect the surrounding environment?
Tice: Whether you are considering a dam removal, the construction of a new dam or the modification, replacement or other improvements to an existing dam, you must consider the environmental effects, the stakeholders who have interest in that dam or related reservoir, and the regulating bodies that may be part of the decision to remove or otherwise alter the dam.
Impacts from a dam removal could result in:
- Construction-related emissions affecting air quality and greenhouse gas levels, contributing to climate change
- Construction-related traffic
- Alterations to water supply and water availability
- Changes to energy production
- Water availability for wildfire response
- Changes to aquatic and adjacent terrestrial habitat conditions, which would then affect the flora and fauna species that rely on those ecosystems
- Changes to recreational opportunities within or adjacent to the reservoir
- Increases to flood potential and general changes to flood management
- Impacts to water quality and sediment transport
The National Environmental Policy Act sets a framework to consider those physical, cultural, social and economic impacts that may result from the removal of the dam. Effects to climate change as well as surrounding communities are also considered in a NEPA review.
What measures need to be taken to avoid or mitigate effects?
Tice: The NEPA process would include a detailed analysis of the existing conditions and the potential changes or impacts. The lead agency would consider alternatives to achieving the purpose and need of the dam removal effort and specifically alternatives that may achieve similar results with less impact. Alternatives considered may include different approaches to removing the dam, replacing or repairing the dam, and they will always consider not removing the dam at all, which acts as a “do nothing” approach to serve as a comparison if nothing is done.
In addition to evaluating this broad range of resource impacts across these alternatives, the lead agency proposing the dam removal is required to identify mitigation measures that would minimize or otherwise avoid any major or significant impacts to the environment or communities.
There are regulating bodies, including but not limited to the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service, the National Marine Fisheries Service and tribal entities, that would likewise have input into the most effective, practicable and least impactful approach to removing the dam. Approval of the dam removal approach requires the approval of these regulating bodies, and thus they may require the completion of certain conditions or measures to minimize, avoid or otherwise compensate for impacts resulting from the dam removal. Likewise, stakeholders, which may include surrounding communities, municipal agencies, state and local governments, water users, non-governmental organizations, recreational users and more, would also have an interest. Engagement with regulating agencies and stakeholders is an important part of the NEPA and regulatory permitting process, giving the agency proposing the dam removal the opportunity to gather important information from those most affected and interested.
The environmental clearance process can take time; however, the overall intention is to complete the removal in the most responsible manner possible. The optimal time to start thinking about these environmental requirements is during early project planning, before you really need them.
As the climate continues to change and flood/drought cycles become less predictable, what can we do to provide for a more resilient water supply?
Beduhn: While some dams may be eligible for increased storage, there is a bigger focus on off-channel storage to capture excess runoff for future beneficial uses and to preserve the natural functions of the floodplain and river systems. Infiltration of floodwaters is another unique opportunity. During the recent high runoff events in California, areas of high recharge potential were purposely flooded to replenish aquifers. Addressing climate variability will necessitate a variety of adaptation solutions.
Tice: There are many studies being done on how to retain and store water in ways we haven’t been able to before. One of the more exciting areas of research is the use of Forecast-Informed Reservoir Operations modeling to change the way water supply is managed today that would bring flexibility to reservoir operations as we currently know them. Specifically, instead of relying on historic conditions at a given reservoir, which typically dictates a water storage and release plan, FIRO would allow for forecast modeling to recommend more nimble interpretation of which water should be retained in a reservoir and which should be released. This would not only provide for a more adaptable and reliable supply of water, but also a reduced risk of flood and a more responsible flood management process.
With regard to dam and levee safety, can you explain the importance of having a focus on reducing loss of life vs. economic benefit?
Behr: Dam and levee failures often result in significant multidimensional consequences. In addition to life-safety criteria, the exposure of economic losses can also be valued relative to costs of improvements to help justify and prioritize actions. Failure consequences can include direct owner impacts (e.g., emergency response and business restoration), environmental (e.g., short- and long-term impacts to habitat and species) and economic (e.g., lost profits and wages). In some contexts, supplemental analyses can also consider approaches valuing human life (e.g., injuries and loss of life) in similar ways to other federal agencies such as the U.S. Department of Transportation, U.S. Environmental Protection Agency and others. To make informed decisions, risk evaluation should consider all such consequences in monetary terms to compare against costs.
Equity evaluations should also be undertaken to better understand the distribution of consequences among those affected by failures. Economic methods that account for the income of those affected by a failure would better represent the societal value of a project. Such approaches to equity valuation provide an alternative insight on the value of a project that contrasts with standard approaches that tend to find greater economic justification for projects that benefit neighborhoods with higher income and wealth, as evident in property values.
Osmun: To wrap up this point, one of the primary guiding principles of a risk-informed dam safety program is that life safety is paramount. When owners have this in mind, it adds clarity to decision-making. The potential for loss of economic benefits must certainly remain an ongoing consideration. At HDR, we have found that a portfolio risk analysis is an effective way to focus a dam and levee safety program on critical areas of maintenance. This approach allows a dam owner to ignore the noise and focus on reducing risk. Used by the country’s top dam owners, the approach comes with a proven track record of helping owners prioritize and justify funding for dam improvement projects.
National Dam Safety Awareness Day is a call to action to improve the safety of dams and levees. New methods and solutions, combined with more robust financing opportunities, are making it possible to “pull over,” investigate and remedy dam and levee safety concerns. We join our industry colleagues in encouraging dam owners to become better-informed owners, and we are committed to continued stakeholder engagement, education and capacity building to keep our dams and levees safe now and for generations to come.