In 2017, the American Society of Civil Engineers (ASCE) completed its quadrennial infrastructure report card, giving American infrastructure a “D +” overall, and a slightly lower “D” for the “Dams” category. With 90,580 existing water impoundments in the US, there is need and opportunity to undertake a variety of activities at all levels of government and across multiple sectors in order to develop a systematic approach to dam safety, operations and maintenance, water supply, hydropower production, and ecosystem health on the nation’s rivers and streams.
Considering that seven out of 10 dams will be over 50 years old by 2025, it is necessary to recognize that while many of these structures continue to provide invaluable functions, others may pose more safety-related, economic, and environmental risks that outweigh the benefits. The ASCE dam report card estimated that it will require roughly $45 billion to repair aging high-hazard potential dams—those that have the potential for loss of life as a result of failure. These dams represent only 17 percent of all water impoundments in the country, meaning the overall infusion of funding necessary to optimize all of the nation’s existing dam infrastructure is a much larger figure.
The failure of the spillways at California’s 770-foot tall Oroville Dam earlier this year after reservoir levels abruptly rose 50 feet, and the resulting evacuation of 188,000 people downstream, brought into sharp national focus maintenance issues associated with aging dam infrastructure. In 2005 three environmental groups filed a complaint with the Federal Energy Regulatory Commission (FERC), alleging that the dam’s spillways had been inadequately maintained and were in need of improvements. The groups filing the complaint requested that the dam’s auxiliary spillway be lined, but FERC rejected the request for cost-saving reasons upon consulting state and local agencies. To date, California’s costs include a $275 million construction contract to repair the spillways, which was awarded in April. With reimbursement of repair costs still yet to be sorted out, California has requested that the federal government pay up to 75 percent. Questions as to whether taxpayers or water contractors receiving benefits will pay for repairs loom and have no doubt created tension within the state.
At the same time that the ASCE is giving US dams a “D” grade, the Department of Energy’s (DOE) Hydropower Vision Report found that US hydropower generation could grow from 101 gigawatts (GW) of capacity to nearly 150 GW between today and 2050 through a combined effort to increase hydropower’s contribution to the nation’s clean power generation portfolio via economically and environmentally sustainable growth by optimizing the use of existing infrastructure. The Report estimates that this level of growth would result in savings of $209 billion from avoided greenhouse gas emissions alone. However, with many dams aging and in disrepair and a movement towards removing obsolete dams gaining momentum, there is a fairly urgent need to evaluate costs associated with dam maintenance and safety considerations that potentially limit a dam’s intended functions prior to investing in hydropower facilities.
Federal bodies like the US Army Corps of Engineers (USACE) and FERC have existing processes in place to evaluate the costs and benefits of a dam. For example, FERC licensing decisions evaluate multiple management alternatives, which may require dam owners and operators to allow higher flow volumes to pass through a dam, install migratory fish passage infrastructure, or make safety improvements. All of these considerations have the potential to limit water storage capacity or hydropower production, or to require dam owners to invest considerably in capital expenditures. These evaluations also include impact assessments that evaluate the benefits and costs to the many parties affected by each management alternative. As a result, some dam owners have found that removing a dam makes more sense than leaving it in place.
Recently, companies have been installing generators on existing dams or building small hydropower projects. This trend and DOE’s recognition in its 2016 Hydropower Vision Report of the hydroelectric opportunities on existing infrastructure indicate that there is considerable opportunity to increase domestic renewable energy supply in this space. According to DOE, dam operators prioritize the following objectives for hydropower operations and maintenance based on the following hierarchy: operational safety, environmental support, reliability, and maximizing value and performance. The Report states, “Hydropower O&M activities are evolving in response to multiple drivers of change, including cost reduction; power system reliability and security; ancillary grid services and flexible operation; increasing environmental needs; and decision making amidst uncertainty.” Thus, with safety as the top priority for dam managers, and cost reduction seen by DOE as a principal driver of change in the safety arena, there is a clear nexus between the need for proper maintenance of existing dams to ensure safety requirements are being met and a dam realizing its intended benefits.
Given the state of aging dam infrastructure in the US, it is necessary for dam owners to evaluate dam safety concerns proactively. The failure of the Oroville Dam spillways illustrates how costly it can be to defer on proper dam maintenance and safety. In addition, in applying these lessons to future management decisions and investments, there is opportunity to maximize existing infrastructure in terms of operational efficiency and increased hydropower production.