The 2024 Virginia General Assembly requested a study to assess harmful algal blooms (HABs) in Smith Mountain Lake (SML), a reservoir created by damming the Roanoke River. Harmful algal blooms have algae and cyanobacteria that produce toxins that may adversely affect human health through consumption of contaminated water or shellfish. The Virginia Water Resources Research Center (Water Center) at Virginia Tech worked with the Virginia Department of Environmental Quality (DEQ), the Virginia Department of Health (VDH), and the Smith Mountain Lake Association (SMLA) to evaluate conditions that may have led to HABs in the past and list recommendations aimed at preventing potential HAB occurrences in the future. Background information for this study was provided in a previous news post (April 8, 2025).
As part of the project, the Water Center developed the SML Webtool to store and share data and analyses for the lake’s stakeholders. The tool includes the following: an interactive map that allows users to explore data from DEQ monitoring sites; view chlorophyll levels across the lake as obtained from satellite images on June 2, 2023; see total phosphorus data from Ferrum College tributary water quality monitoring sites; and observe land cover information for the watershed.
The Water Center also developed a report to summarize the goals of the project and accomplishments achieved during the one-year study. Data obtained from various sources indicate that SML has the potential to support multiple and prolonged blooms of cyanobacteria when conditions are favorable; however, data do not indicate, at this time, that HABs are a recurring issue in SML. Data collected within the lake and watershed for the past several decades were analyzed in an effort to identify the major factors and conditions leading to the occurrence of blooms in SML. The report also highlights monitoring and management approaches to consider in an effort to prevent the formation of future HABs within the lake.
