Millions of gallons of water rushed out of the Kinzua Dam every minute for eight hours straight into the Allegheny River.
The outflow caused the Allegheny River to rise by almost two feet. The water pushed out of the dam with massive force, resembling giant firehoses opened to full blast.
This water release event was seven years in the making, a perfect storm of conditions that allowed water quality experts to replicate a spring pulse.
“We’re normally fairly restricted in how water is released from the dam, so we don’t see the normal pulses rivers see,” said Andi Fitzgibbon, a biologist with the U.S. Army Corps of Engineers Pittsburgh District’s Water Quality team.
The Kinzua Dam exists to control water flow to reduce flooding, but with recent heavy rains, the Water Quality team pounced on an opportunity to simulate a spring pulse.
Spring pulses are natural phenomena that typically occur in temperate climates and during early spring. As the weather warms up, rivers and tributaries receive more precipitation and runoff water, sending a cue to aquatic species and other parts of the ecosystem by moving sediments and nutrients.
This movement encourages vegetation growth and provides post-winter habitats for various animals. For instance, the paddlefish uses the spring pulse as a cue to spawn and have baby paddlefish.
However, because of the Kinzua Dam, the Allegheny River had not seen a natural spring pulse since the dam was constructed in 1965.
To generate the pulse, dam operators increased the dam’s outflow from 9,000 cubic feet per second (CFS) to 15,000 CFS for eight hours. That resulted in 3.2 billion gallons of water released into the river during those hours, equivalent to nearly 5,000 Olympic-sized swimming pools.
The district’s water management team modeled the operation to ensure the artificial pulse would not impact the reservoir’s summer pool or cause flooding.
To test the effects of the pulse, the Water Quality team, consisting of biologists, collected water and tested samples downriver. They threw buckets into the river, poured samples into little bottles and cylinders, and tested the samples using machines on the back of their trucks.
“All the different animals and plants living within stream ecosystems have evolved alongside these disruptive water events,” said Carl Nim, a biologist with the district’s Water Quality Team. “They’ve found ways to coexist with these disturbances and, in a lot of cases, thrive.”
Simulating the spring pulse is a significant milestone for the district. Kinzua Dam operates according to congressionally approved flood-control protocols based on flooding, navigational and environmental conditions.
The dam has prevented more than $1.3 billion in flood damages since its construction in 1965. However, because the dam holds back reservoir water, it prevents spring pulses from occurring naturally.
“Returning that normality to the river is really cool to me as an ecologist and for the ecosystem. This project has been sitting on the books for a long time, and it’s wonderful to get to do this first pulse,” Fitzgibbon said.
Despite the myriad benefits of the spring pulse, organizing it presented a lot of challenges. The simulated pulse took more than seven years to coordinate because it required the reservoir to meet specific water conditions and historical-flow regimes without sacrificing its operational responsibilities.
“The hard part is to balance the pulse with all of the other mission requirements the corps has,” Nim said. “One of those is flood control. We don't want to create flood problems on the river, but we also want to provide these ecosystem benefits. It's a real balance in terms of making the Goldilocks scenario with the right amount of water to mimic these spring pulses but not flood out anybody.”
Nim said organizing the pulse required coordination and quick response. For example, the Water Quality team knew they could release the spring pulse when heavy rains hit the region, raising the reservoir level two feet above the summer pool months ahead of schedule. That meant the reservoir was suddenly holding back a lot more water that the team could use for the pulse.
“We didn’t have a lot of time to work with when the rain came, so when we saw that forecast, that mid-latitude wave cyclone coming across the United States bringing two inches of rain, we needed to have all of our ducks in a row, so we could get the thumbs up from everybody involved,” Nim said.
The Pittsburgh District was not the only organization interested in the pulse. Several Ph.D. students from the University of Pittsburgh conducted their own water-sampling tests near Kinzua Dam. Nim coordinated with the university to help coincide their research with the water’s release.
“Without the pulse or spring events like it, outdoor recreation activities will be severely impacted, and these beautiful ecosystems could deteriorate,” said Abby Yancy, a Ph.D. student at the University of Pittsburgh.
“The pulse is important for many beloved sensitive aquatic and terrestrial organisms like plants, fish mussels,” she said.
For Nim, the new initiative is an exciting step for the corps’ role in improving water quality for the region. He hopes to see it move forward – both in the district and with water quality practitioners as a whole.
The Water Quality team is an essential part of the district’s mission. The team travels weekly across the district’s 26,000-square-mile span to collect samples to assess “bio-indicators” that represent ecological quality.
“We collect a bunch of different parameters,” said Nim. “So we'd look at pH, acidity, alkalinity, turbidity, dissolved oxygen, specific conductivity, nutrients, as well as metals. Those just scratch the surface of describing what we look at.”
The collected data is used to make reservoir-management decisions, such as how much water to release to improve downstream water quality and keep the waterways clean. One of the mantras Nim says to teach others about how water quality works is “dilution is the solution to pollution,” which means that adding the flow of clean water to a stream will naturally dilute and purge pollution in that area.
Applying this principle has helped the corps improve water conditions for decades. The region has seen drastic improvements over the years through its efforts, especially thanks to the Clean Water Act of 1972. Clean water from reservoirs has helped areas impacted by industries and acid mine drainage, making the drinking water safer for nearby communities.
“To this day, we release more water in the Allegheny River during the summer to improve those conditions. While it does alter the hydrologic regime of the river, it improves conditions markedly for aquatic species and communities alike,” said Nim.