PITTSBURGH – Every rainstorm hits a region differently.
Some storms cause flash flooding that swallow streets and damage property, while others pass by unnoticed, even if they bring the same amount of downpour to the same general region.
It is often difficult – if not impossible – to predict how future storms might impact a community. However, the Pittsburgh region is better protected from flooding thanks to the U.S. Army Corps of Engineers and a system of reservoirs designed to capture rainfall to mitigate flood risks.
A SYSTEM OF RESERVOIRS
The devastating St. Patrick’s Day Flood of 1936 prompted Congress to authorize USACE to construct a network of flood-reducing dams and reservoirs.
Today, 16 strategically-placed reservoirs across the Pittsburgh District capture rain, snowmelt and runoff throughout the year. These reservoirs span into northeastern Maryland, eastern Ohio, western Pennsylvania, and northern West Virginia.
The reservoirs rely on the region's Appalachian Highlands to maximize water collection, storing about 30 percent of rainfall across a 26,000-square-mile footprint.
“For example, if 10 inches of rain fell uniformly across the entire district, our reservoirs could capture about 3 inches of it,” said Nicolas Lazzaro, chief of the Water Resources Section for the Pittsburgh District.
However, storms rarely distribute rainfall evenly. The amount of water a reservoir holds depends on a storm's location, speed and movement, not just total rainfall.
“We could capture more than 30 percent of a storm, depending on where the rain event occurs,” said Col. Nicholas Melin, commander of the Pittsburgh District.
For example, the Kinzua Dam, which forms the Allegheny Reservoir northeast of Pittsburgh, can capture significant rainfall. Conversely, other areas that lack dammed reservoirs may be less protected.
Predicting the damage from future storms remains difficult because of too many unknown variables. The district instead uses its reservoirs’ historical performance to depict their value.
Since the 1930s, Pittsburgh District reservoirs have prevented $48 billion in flood damage. Most recently, Pittsburgh saw 7.29 inches of rain in early April 2024, one of the heaviest rainfalls in decades. The Conemaugh Dam east of Pittsburgh captured enough runoff to prevent six feet of floodwater from reaching downtown, saving more than $250 million in damages.
The district’s dam safety team regularly monitors each dam’s performance. They inspect every dam once a year, and they perform more intense inspections every five and 10 years. The process involves a complete assessment of every dam function, from gate operations to the stability of the dam itself. Their monitoring increases during heavy-rain events to ensure all dams perform as designed.
Without these federal dams, heavy rains could quickly overwhelm the Allegheny, Monongahela, and Ohio rivers.
RAPID RESPONSE TO STORMS
The district’s dams are not “set it and forget it” structures. They require daily operation and monitoring.
“Our team works 365 days a year, actively managing water levels to reduce flood risks for Pittsburgh and the surrounding region,” said Melin.
During ideal conditions, reservoirs hold storm runoff with minimal downstream impact.
Managing reservoirs still requires proactive decisions, especially in the early hours before, during, and after a downpour.
A dedicated team of engineers, park rangers, and emergency response managers monitors water levels and collaborates with agencies like the National Weather Service to prepare for incoming storms. NWS projects the amount of rainfall a storm will bring and how that rain will impact river levels. The Pittsburgh District, in turn, adjusts its dams’ gates to keep as much rain as possible from overflowing downstream rivers.
Yet, reservoirs have a limited capacity, so the district sometimes releases water in advance to make room for additional rainfall. While this may seem counterintuitive, these calculated releases minimize downstream impacts and ensure reservoirs remain effective during storms.
Based on those releases, the Water Management team can project river levels, which impact navigation and could prompt emergency response offices to act. Projecting the final river levels requires coordination between various agencies until the end.
EMERGENCY RESPONSE
Once a reservoir reaches capacity, water must go somewhere.
“When we receive a ‘high-water notification’ from Water Management, that’s a trigger for us to start our emergency actions,” said Julie D’Annunizio, an emergency response specialist for the Pittsburgh District.
Some dams are designed with an overflow spillway, which lets water escape downriver in an “uncontrolled” fashion. Other dams have upper gates, known as “crest gates,” that open to release excess water.
In either case, that water could overwhelm downstream communities. That is when the Pittsburgh District’s Emergency Management Office comes into play. Their team coordinates with first responders and agencies at every level of government.
“Flooding is our number one hazard we plan for, we train for, we rehearse, we exercise for this region,” said D’Annunzio.
“We work with our local partners to exercise of how we would respond to protect our infrastructure and our employees, but also our communities. We have a whole team of engineers that can assist communities, counties in the state with flood risk reduction,” she said.
During flooding events, USACE can provide sandbags, temporary barrier material and water pumps. Specialized engineers and other technicians work with local sponsors on levee safety, also known as local flood protection projects. The safety team inspects and assesses levees to identify performance deficiencies and collaborates with sponsors to address issues.
“I've been in the military now going on 25 years, and I've served in a lot of different places, but I've never had a chance to serve the American people directly in their homes as much as I have here,” Melin said.
Engineers offer technical assistance on flood-related infrastructure to help local and regional partners implement flood risk management solutions. They can also answer questions about resources available and collaborate on critical decision-making data.
“We're really, very deeply tied into the local communities in this region,” Melin said.
Once river levels reach certain conditions, lock-and-dam facilities adjust or shut down their operations to maintain safe navigation. They coordinate with the U.S. Coast Guard and commercial industries to communicate closures. Local authorities are responsible for road closures, evacuations and other first-responder decisions, where USACE is typically not involved directly.
“Counties do a great job to prepare hazard plans, and they work with their municipalities and the state emergency agencies on that input,” D’Annunzio said. “They want to do what’s best for their communities and their citizens to improve their resilience as much as possible.”
USACE employees attend those hazard plan meetings and participate in the Silver Jackets program, a state-led interagency teams focusing on nonstructural floodplain management and risk communication. The forum is used to coordinate requests from local communities, collaborate on interagency solutions, and share information.
Engineers are regularly working on studies year-round to help improve community infrastructure.
“We are seeking ways to be proactive, not just to respond to an event, but to help those communities to be resilient against the impacts of future events. Sometimes it takes a big rain event for a local community to realize they have a problem,” Melin said.
To receive elevated federal assistance, state governments must declare a state of emergency and obtain congressional approval. Upon authorization, USACE collaborates with FEMA to deliver recovery and relief efforts.
FLOOD RECOVERY EFFORTS
The Pittsburgh District’s work extends beyond mitigation or prevention.
Once a state of emergency is declared, FEMA can provide additional federal aid and USACE comes alongside to provide disaster support.
“When the president declares a disaster, we step in and respond, and we do it in a number of different ways,” Melin said.
The Pittsburgh District coordinates the install for emergency power generators not only in the immediate region, but across the United States and its territories. Additionally, USACE coordinates debris removal, assists in search and rescue, provides infrastructure assessments, directs “Blue Roof” tarp installations, provides water and wastewater treatment facility assistance, and offers various other engineering or technical assistance.
“Before any weather event impacts the United States, FEMA and the Army Corps of Engineers are prepared to deploy,” Melin said.
USACE activates a crisis action team to respond. The team sets up an emergency response center with monitors displaying weather maps, flood zone diagrams, operational graphs, and track information that changes by the hour.
The Pittsburgh emergency team trains on a different scenario each year while increasingly incorporating other agencies into their training.
It is impossible to predict when the next storm will hit the region or even how much flooding or rain it will bring, but regardless of conditions, the U.S. Army Corps of Engineers Pittsburgh District is ready to respond.
“Every storm is unique, but we have teams that work 24/7, 365 days a year actively monitoring water levels,” said Melin. “Our teams are working midnight to midnight, every day, watching the river gages and our reservoirs, and if we see an extreme event coming, we’re standing up our emergency operations and jumping into action.”