Written by Adeline Muras, VWRRC Intern
In 2024, the Virginia General Assembly included funding for a research study assessing algal blooms in Smith Mountain Lake, Virginia. The Virginia Water Resources Research Center (Water Center) at Virginia Tech is working in conjunction with the Virginia Department of Environmental Quality (DEQ), the Virginia Department of Health (VDH), and the Smith Mountain Lake Association (SMLA) to study harmful algal bloom (HAB) incidents reported at Smith Mountain Lake during the summer of 2023. The work includes an evaluation of conditions that may have led to HABs in the past and a list of recommendations aimed at preventing potential HAB occurrences in the future.
Smith Mountain Lake is located in Bedford, Franklin, and Pittsylvania counties and has over 500 miles of shoreline. It has two main branches, the Roanoke River arm and the Blackwater River arm. In 2023, the VDH issued a no-swim advisory for the Blackwater arm of the lake because of elevated-cell counts of potential toxin-producing species. Portions of the Blackwater arm remained under the no-swim advisory for nearly the entire summer, June 6, 2023, to August 28, 2023.
Algal blooms occur in water bodies when colonies of algae or cyanobacteria (often called “blue-green algae”) proliferate. Not all algal blooms are considered harmful. Harmful blooms result when the algae or cyanobacteria produce toxins that are harmful to people, domestic animals, and/or wildlife. In fresh waters, cyanobacteria are the main culprits of HABs. Some species of cyanobacteria can produce liver and/or neurological toxins that can harm humans who ingest the toxin or come into contact with it. To alert the public of the risk of an algal bloom, VDH issues recreational advisories when thresholds for toxin-producing algae are exceeded.
Factors that cause HABs to grow include high nutrient levels in the water, elevated water temperatures, slow-moving water, and sunlight. To learn more about the causes of HABs, you can visit the DEQ’s website by clicking here. The VDH operates an algal bloom surveillance map for Virginia that is regularly updated May-October and can be found here.
Pictured below are examples of what algal blooms may look like. They often appear like spilled paint or scum on the surface of the waterbody but are not always visible. It is not possible to tell if an algal bloom is harmful simply from its appearance. The water must be analyzed for toxins.
Figure 2. Photos above showing algae blooms are courtesy of Smith Mountain Lake Association.
The Water Center’s team undertaking the study of Smith Mountain Lake includes Daniel McLaughlin, associate director of the Center and associate professor in Forest Resources & Environmental Conservation (FREC); Yang Shao, associate professor in Geography; Jane Walker, research associate with the Center; and Kevin McGuire, director of the Center and professor in FREC. They are collaborating closely with personnel from the DEQ and VDH, as well as volunteers from the SMLA, and alongside an advisory committee of academic experts from various institutions across the Commonwealth.
The main goal of the study will be to provide short- and long-term strategies to prevent future formation of HABs in Smith Mountain Lake. The study will involve analyses of water quality and remote sensing data from the lake as well as modeling the impacts of land use within the lake’s watershed. A report that summarizes the work accomplished and findings will be provided to the General Assembly this summer.
