Pumping oxygen into the bottom waters of Southwest Virginia’s drinking water reservoirs can reduce treatment costs and help fish and other aquatic life, according to an interdisciplinary research team with the Global Change Center at Virginia Tech.
The team has installed oxygenation systems in three reservoirs that serve Roanoke and surrounding county residents — Carvins Cove, Falling Creek, and Spring Hollow — and are monitoring them to see how increased oxygen levels affect the amount of metals in the water.
The Appalachian region’s geology results in high levels of iron and manganese in sediment that lines the bottom of the reservoir. If these metals are released from sediment into the drinking water, they can cause taste, staining, and odor issues.
However, pumping additional oxygen into the bottom waters of the reservoirs can keep these metals safely locked up in the sediment, even in warmer temperatures.
“Climate change is causing natural waters to warm, and warm water can’t hold as much oxygen as colder water can,” said Cayelan Carey, an assistant professor of biological sciences in the College of Science. “We’re testing these oxygen systems to see if they might provide an effective way to combat warming temperatures and provide people here with the best water possible in the future.”
The team — which includes ecologists Cayelan Carey and Quinn Thomas, an assistant professor of forest resources and environmental conservation in the College of Natural Resources and Environment, geoscientist Madeline Schreiber, environmental engineer John Little, and their students — recently received a seed grant from the Global Change Center to purchase a weather station for the project.
The station, located at Falling Creek Reservoir, allows them to plug real-time weather data into their models, which are constructed to pinpoint the best time to oxygenate the water. Previously, the team had relied on data from the weather station at the Roanoke-Blacksburg Regional Airport, which is 11 kilometers away, subject to different wind currents, and at a different elevation.
“Our seed grant program is designed to facilitate new interdisciplinary collaborations among faculty from all corners of campus” said Bill Hopkins, director of the Global Change Center. “The water reservoir team has been able to use their seed funding to launch a highly successful ecosystem-scale manipulation that is providing benefits to both the environment and society. They are now positioned to solve even bigger, more complex problems related to water resource management that have global implications.”
The oxygenation systems have already been a great investment, according to Jamie Morris, water production manager at the Western Virginia Water Authority (WVWA). The technology has reduced the amount of chemicals the authority has to apply to the water to treat it, which saves consumers money.
“We are really excited about our strong partnership with Virginia Tech on this project,” said Morris. “Not a lot of water utilities and agencies are looking at this, and certainly not in the form of the detailed information we’re getting from Virginia Tech. We’re grateful to receive this information, and also happy to help the students with their research projects.”
Approximately 10 students are working on the project.
Mary Lofton, of Crozet, Virginia, a doctoral student in Carey’s lab, is involved with assessing how phytoplankton in the water are responding to aspects of climate change, such as temperature change and increased storm intensity. She helps develop lake model scenarios with a focus on predicting future phytoplankton community dynamics.
“To me, it's really powerful to see the research we conduct at Falling Creek Reservoir getting communicated to the water authority to inform their management decisions on a weekly basis during field season,” said Lofton, who is also an Interfaces of Global Change Fellow. “Our partnership has taught me what water quality information is most helpful from a reservoir management perspective, and how best to communicate our research so that the water authority has the tools they need to make good management decisions going forward.”
The water authority has partnered with Virginia Tech since the 1990s, when Little and his students first designed the oxygenation systems and placed them in Spring Hollow, Carvins Cove, and Falling Creek reservoirs. Former doctoral student Paul Gantzer ’08 even went on to start a company, Gantzer Water Resources Engineering LLC, based on the technologies he helped develop as a student at Virginia Tech.
“We have developed models for each of these systems and use them to improve the design and operation of these systems in the WVWA reservoirs as well as in other reservoirs around the world,” said Little, the Charles E. Via Jr. Professor of Civil and Environmental Engineering in the College of Engineering.
“Working within an interdisciplinary group has allowed us to learn how each of our disciplines affects the reservoir ecosystem,” said Schreiber, a professor of geosciences in the College of Science. “And personally, it's been incredibly rewarding to apply fundamental knowledge on ecological and biogeochemical processes to help improve drinking water quality for our region.”