Earlier this year, the Association of State Dam Safety Officials (ASDSO) expressed its concern that government action was directly affecting dam safety programmes. As the Trump Administration worked to ‘dismantle the scientific enterprise’, federal experts were losing their jobs or being encouraged to leave the federal government.
These actions, ASDSO agreed with the American Geophysical Union, were weakening the economy, undercutting national security, and endangering the health and well-being of all Americans.
Sustained commitment needed
Twenty-four federal agencies across the US are responsible for coordinating dam programmes. They also own and/or regulate over 5000 dams and contribute to improving public safety and the science of dam engineering through research and data analysis. Scientists and engineers across various departments, such as the Department of Commerce, Defence, Army, Interior, Energy, Agriculture, plus the US Power Marketing Administrations, are ultimately responsible for the safety of 90,000 dams across the US.
“Without a sustained commitment by those within the engineering and scientific communities overseeing these structures, as well as those making long-term policy and funding decisions, we are indeed endangering the health and well-being of the American public,” Lorie Spragens, ASDSO’s Executive Director said.
“It is well known within the dam safety community that a series of dam failures in the 1970s and ‘80s collectively killed more than 500 people and caused billions of dollars in property and economic damages. It was clear at the highest levels of federal and state government that the way to reduce risk and improve public safety was to vastly improve leadership and funding and increase the expertise in the scientific fields touching dam engineering. And we’ve done that,” Spragens went on to state. “We have reduced risks associated with dams in the past 40 plus years. But this must be a constant push to improve, as dams age, and populations grow below dams. We don’t want to go back to the ‘70s.”
ASDSO says it wanted its members and colleagues who work in the US government to know how saddened it is by the situation they find themselves in, but also wanted them to know there is still a dam safety community supporting them – and its work and commitment won’t stop. ASDSO has opened a new job posting marketplace (https://damsafety.org/careers) which is free and open to all who want to use it. It has also created an anonymous form where those directly or indirectly impacted can share thoughts, stories, and suggestions with ASDSO leadership.
“These disruptions will hopefully not last,” Spragens said. “We encourage everyone to tell your representatives and senators how important these roles at the federal level are. And remind them that suspending funding for federal grants will make Americans less safe, secure and prosperous. Our voices need to be heard.”
US Army Corps gets to work
Demonstrating the important work it does in relation to dam safety, the Omaha District of the US Army Corps of Engineers recently performed the first of two periodic inspections at Branched Oak Dam in Nebraska.
“We look for any issues that might affect the performance of the dam, especially during extreme conditions where the reservoir rises above the normal pool,” says dam safety engineer Matthew Borys.
The periodic assessment is led by the Institute for Water Resources’ Risk Management Centre, while the Omaha District is the technical lead. The inspection team includes geotechnical, structural and hydrologic engineers as well as an economist who analyses the consequences of a dam breach and the potential effects to downstream communities in the event
of a flood.
The team walked the entire length of the spillway, abutments and embankments looking for any deficiencies including cracking, active erosion or settlement, depressions where erosion could start, and unwanted vegetation. A structural engineer also inspected other features of the dam including the intake structure and outlet works conduit where they looked for deteriorating concrete.
Following the inspection, a week-long potential failure mode analysis was conducted to review inspection observations and existing data to brainstorm potential failure modes for the project.
According to Borys, the most common failure modes identified for the system of these Salt Creek dams are overtopping that may result in a dam breach, followed by spillway erosion that may cause a breach through the spillway, and finally, concentrated leak erosion along the conduit which is an internal seepage failure mode.
“We are brainstorming any possible ways the dam could have an unintentional release of water,” Borys said. “We discuss the existing conditions of the outlet works, consisting of the intake, conduit, and stilling basin, along with the embankment, foundation, and abutments and how these features will perform at various pool elevations.”
Branched Oak Dam was built in 1967 by the US Army Corps of Engineers as part of the Salt Valley Lakes flood control project. It captures water from Oak Creek, a tributary of Salt Creek, during high runoff events to help control flooding. It is one of ten Salt Creek dams that work together to help reduce flood risk for the city of Lincoln and surrounding communities.
The 7.3km2 Branched Oak Lake sits behind the dam and is part of the Branched Oak State Recreation Area managed by the state of Nebraska’s Game and Parks Commission. The area provides fish and wildlife habitat, water resource benefits, and recreational opportunities such as fishing, boating and camping.
Borys emphasised that while there hasn’t been any significant flooding from Salt Creek in recent years, dams cannot prevent all floods.
Awareness Day
In the US, a Dam Safety Awareness Day is commemorated each year on 31 May, serving as a reminder that while dams provide valuable services to communities nationwide, none are risk free.
Speaking about the US Army Corps of Engineers Dam Safety Programme, Louisville District Dam Safety Chief Kate Brandner said: “The Dam Safety Programme’s primary goal is to ensure the safety of the dams in our inventory, prioritising public safety. We do this through a risk informed approach; constantly assessing the projects. Through risk assessments, we consider external events and what risks they pose to the projects, like large flood events, earthquakes, along with the performance of the projects, assessing consequences that would occur should an issue develop at a project. We use all available resources to ensure that the projects are performing as well as they can and document what needs to be done to have continued good performance of the projects.”
In addition to Brandner, the Louisville District Dam Safety team consists of 12 other members.
“Leading teams through periodic inspections and day-to-day requirements in dam safety is incredibly rewarding,” Brandner said. “It enables me, as an office worker, to engage with operations personnel that know and care about their projects, and hopefully provide them with some guidance as to how we as an organisation can continue to have our dams performing safely. I have found that I can be a sounding board, appreciating their assessments of issues and working to ensure a path forward to any necessary repairs will be effective.”
With 17 flood risk management dams across Kentucky, Indiana and Ohio, the Louisville District Dam Safety team conducts rigorous inspections, maintenance and rehabilitation to prevent potential failures and reduce flood risks. In fact, since their construction, these 17 lake projects have helped prevent more than US$3.9 billion in flood damages.
This spring, many members of the Dam Safety team mobilised to support operations staff at the projects to ensure continued operations through record-high pools and unprecedented rainfall events. “The flood risk management projects performed great through the ongoing event, and that is in no small part due to the people that were out there during the flood event, and the great staff we have working on the projects every day,” Brandner added.
The Louisville District also implements the dam safety mission over a total of nine navigation locks and dams on the Ohio River and the Green River.
USACE maintains the National Inventory of Dams which documents all known dams in the US that meets certain criteria. This database provides the public with the ability to search for specific data about dams and serves as a resource to support awareness of dams and actions to prepare for a dam related emergency.
“Being part of a team that shares a passion for public safety is exactly what I was looking for in my career,” says Megan Jones, Louisville District geotechnical engineer and Greater Miami River Basin coordinator. “As a Certified Floodplain Manager, and as someone who grew up around lakes and rivers, flood mitigation has always been a special interest of mine. That’s why I strongly believe in the importance of inspecting, assessing and understanding the risks associated with each of our Flood Risk Management projects. We not only use this knowledge to inform ourselves as dam tenders, but also share it with local communities – empowering them to make informed decisions about their own safety. We work hard to ensure that everyone receives the most accurate and up-to-date information. I couldn’t be prouder to be part of the Louisville District’s Dam Safety Team,” she added.
Rehearsing responses
Two joint exercises simulating potentially catastrophic flood events affecting the Denver metropolitan area were held during February at the Mile High Flood District headquarters in Denver, Colorado.
The exercises, planned and hosted by the US Army Corps of Engineers, Omaha District’s Dam and Levee Safety Branch and Readiness Branch, brought together local, state and federal emergency managers along with local area law enforcement and principal information officers, to meet critical goals in emergency preparedness and response.
“Rehearsing agencies’ responses to exercise scenarios confirms or challenges preparedness plans and identifies improvement opportunities before a real flood or dam emergency,” said Amy Echols, a dam and flood risk communicator with the Omaha District. “These particular exercises helped ensure the practical understanding of roles and responsibilities across emergency level determinations, notifications and responses that would help protect the densely populated communities downstream of the three Omaha District dams in the area, and further down the South Platte River through downtown Denver.”
Briefings by the USACE team preceded the exercises on topics including the dam safety program, dam operations under normal conditions and during a flood event, and emergency action plans. The staff emphasised dams do not eliminate flooding, and many agencies, as well as the public, have roles in reducing flood impacts.
Both exercises, the first focusing on Cherry Creek Dam and Reservoir and the second focusing on Chatfield and Bear Creek dams and reservoirs, presented developing dam safety and flood scenarios. Each began with heavy rain in combination with an unseasonably warm weather melt of record snowpack that caused rapid runoff into the three reservoirs, resulting in historic water levels.
The simulated, progressive scenarios introduced both structural and operational issues at each dam and their related spillways, none of which has been tested to-date under flood flows. The scenarios and several timed injects built up scenes for the district’s own Tri-Lakes Project staff to determine appropriate actions for dam surveillance and operations under strained conditions.
Weather forecasts, evolving hydrologic conditions and other simulated circumstances pressed partner agencies to assess their evacuation procedures, responses to public reaction, and to anticipate significant critical infrastructure and population impacts that could occur in a flood emergency.
“The purpose of the tabletop exercise was to stress the participants with a plausible scenario to determine preparedness,” said Omaha District Civil Engineer Katie Seefus who manages water storage and releases for the Tri-Lakes Projects and who also helped develop the scenarios. “Extreme flood preparedness and response planning and practice is an incredibly important life-safety tool. It builds and maintains critical relationships, tests the effectiveness of the local, state and federal emergency action plans, and allows a better understanding of each agency’s role and what agencies can offer each other to help ensure effective responses to an emergency.”
The Omaha District owns and operates 28 dams throughout the Upper Missouri River Basin. The Tri-Lakes Project dams include Cherry Creek, Chatfield and Bear Creek dams, and are located to the west, south and southeast of Denver. As a system, these dams reduce flood risk for 2.8 million people in the greater Denver metropolitan area.
References
Advancements in dam design and safety for sustainable water resources management in the USA Michael A Reed. International Journal of Hydropower and Civil Engineering 2024; 5(2): 22-27.
