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Nestled at the foot of the Blue Ridge Mountains, Smith Mountain Lake is the largest lake entirely within the Commonwealth of Virginia. Spanning over 20,000 acres with 500 miles of shoreline, the lake’s northern and eastern boundary is marked by Bedford County, while Franklin and Pittsylvania counties define its southern and western edges. Created in 1963 by impounding the Roanoke River with the Smith Mountain Dam, the lake serves multiple purposes, including hydroelectric power, public water supply, and recreation.
Throughout the 1960s and 1970s, the area surrounding Smith Mountain Lake was predominantly rural farmland. In the 1980s, however, the lake’s natural beauty, recreational appeal, and proximity to Roanoke and Lynchburg began to draw increased attention. This surge in interest sparked a boom in residential and commercial development, transforming Smith Mountain Lake into a vibrant and bustling community.
Today, Smith Mountain Lake not only provides electricity and drinking water, it is also home to 21,000 residents and stands as a premier recreational resource. Thousands flock to Smith Mountain Lake each year to enjoy boating, swimming, fishing, and other water activities. The lake’s shores are now dotted with resorts, condominiums, year-round residences, and outdoor industry businesses. The lake’s waters and shoreline also provide vital habitats for aquatic plants, animals, birds, and other terrestrial wildlife.
The rapid growth of this pristine lake community underscores the importance of effective environmental management to preserve water quality, strengthen the shoreline, manage stormwater runoff, and protect the local native biodiversity of the lake and its watershed.
The lake is fed by two main tributaries—the Blackwater River and the Roanoke River. The Roanoke River, the larger of the two, drains a watershed that includes the Roanoke Metropolitan area, while the Blackwater River flows through mostly rural and agricultural land.
In 2023, a significant outbreak of harmful algal blooms (HABs) in the Blackwater River subwatershed raised concerns for the Smith Mountain Lake Association (SMLA). These blooms, primarily driven by agricultural runoff, led to swimming advisories and highlighted the need for a comprehensive approach to managing and mitigating these environmental threats.
Recognizing the urgency of the situation, SMLA sought the expertise of Princeton Hydro. The mission: to investigate conditions that cause HABs, protect the lake from future outbreaks, and ensure the long-term health of this vital freshwater resource.
The project team’s approach began with a thorough review of historical water quality data. Collaborating with SMLA and regulatory bodies including the Virginia Department of Environmental Quality (VDEQ), U.S. Geological Survey (USGS), and U.S. Army Corps of Engineers (USACE), Princeton Hydro compiled a comprehensive dataset. This historical context was crucial for understanding past trends and informing the 2024 Watershed Assessment. SMLA and Ferrum College contributed over 38 years of data through their Volunteer Water Quality Monitoring Program, documenting crucial indicators such as nutrient levels, bacterial counts, and algal blooms. This extensive dataset has been essential in informing effective lake management practices and shaping strategies to address current environmental challenges.
Employing the MapShed model, the team carried out a comprehensive hydrologic and nutrient loading analysis of the Blackwater River subwatershed. They evaluated critical factors, including phosphorus, nitrogen, and sediment levels, to identify and prioritize areas requiring targeted nutrient and sediment management strategies.
To describe its basic function, the MapShed model applies pollutant loading rates to different land cover types, like low-density development or forested wetlands, based on their area. It then uses weather data, soil characteristics, and slopes to adjust these results. The model simulates daily pollutant loads over 30 years using actual climate records, providing monthly and annual outputs. Users can adjust various inputs, like septic system efficiency and population density, to see how the changes affect pollutant loads and water flow.
This analysis laid the foundation for determining effective, focused interventions to curb nutrient runoff and mitigate future HABs.
In March 2024, an Overwintering Incubation Study was conducted to understand cyanobacteria behavior. Sediment and water samples were taken from six nearshore locations known for high cyanobacteria counts in Summer 2023. At each site, the team also documented temperature, dissolved oxygen, specific conductivity, pH, chlorophyll-a, phycocyanin (PC), and phycoerythrin (PE).
The map below identifies the locations of each of the six sampling sites:
For each sample, the lake water was filtered and then incubated with respective sediments to determine the presence and what types of algae may be overwintering. The water and sediment samples were incubated over a period of 15 days at a temperature of approximately 77 degrees Fahrenheit and a light intensity of 2800 lux.
After eight days, the water and sediment samples were removed from the incubator, slightly stirred and then in-situ measurements for PC and PE were collected. These two supplemental pigments are almost exclusively produced by cyanobacteria. While PC is associated with primarily planktonic genera, PE is more associated with benthic genera. Thus, measuring the concentration of these pigments can be used to estimate cyanobacteria biomass as well as provide guidance on the monitoring and management of HABs (planktonic vs. benthic).
After 15 days, the samples were again removed from the incubator, slightly stirred, and then measured for PC and PE to identify and count any overwintering cyanobacteria and determine all the types of algae present.
This study offered critical insights into the conditions that enable cyanobacteria to endure winter and proliferate during warmer months. By understanding the connection between overwintering cyanobacteria and HABs in the lake, we can enhance predictive capabilities and develop more effective management strategies. Two particularly notable findings from the study include:
1. Sediment Composition and Cyanobacteria Growth: Sandier sediments were not conducive to overwintering cyanobacteria, suggesting blooms in these areas likely originate elsewhere in the lake. Conversely, siltier and organic-rich sediments supported cyanobacteria growth, indicating a need for targeted in-lake management measures.
2. Predictive Tools for HABs: Routine measurement of pigments like PC and PE proved effective in estimating cyanobacteria biomass. This information is crucial for long-term monitoring and management, offering predictive tools for HAB events.
Beyond the initial assessment on the Blackwater River, ongoing monitoring of Smith Mountain Lake’s water quality is crucial for understanding and managing the conditions that trigger HABs. SMLA’s Water Quality Monitoring Program developed and managed by Ferrum College continues the work of tracking the trophic state of the lake. Algal community composition, tributary sampling, and bacterial monitoring are part of this comprehensive 38-year effort. Consistent sampling and water quality monitoring can help identify cyanobacteria and akinetes, the dormant spores that lead to bloom formation.
Because the VDEQ budget historically contains no funding for inland waterway HAB research and response, SMLA actively lobbied the Virginia General Assembly for the allocation of $150,000 for the creation of a watershed study. This request was included in the State budget signed in March of 2024 and the work to develop the objectives and scope of the study is underway now.
Community involvement is also vital for maintaining Smith Mountain Lake as a cherished resource. To this end, SMLA has launched “Dock Watch,” a new community science volunteer program designed to monitor HAB activity. Beginning in May of 2024, volunteers have been collecting water samples at select docks around the lake and are examining them to better understand cyanobacteria activity levels and trends. All of the water quality data collected at the lake is from main channel locations. The primary recreational contact with the lake water by residents is at their docks. This data is uploaded to NOAA’s Phytoplankton Monitoring Network, contributing to a national database used for HAB research. This collective effort ensures rapid identification and tracking of HAB activity, benefiting both the local community and environmental research on a national level.
“This project exemplifies a holistic approach to lake management and environmental stewardship, integrating historical data, advanced modeling, and community engagement to prioritize and implement innovative strategies that effectively mitigate HABs and protect water quality,” said Chris L. Mikolajczyk, Princeton Hydro’s Senior Manager of Aquatics and Client Manager for Smith Mountain Lake. “This ongoing work highlights the importance of science-based interventions in preserving our precious natural resources.”
The Smith Mountain Lake Association is a 501(c)3 nonprofit with the mission to keep Smith Mountain Lake clean and safe. Founded in 1969, SMLA is the longest serving advocate for the Smith Mountain Lake community, and its focused efforts help to retain the pristine beauty of the lake and the vibrant local economy. Click here to learn more and get involved.
Over the last two decades, the Princeton Hydro team has improved water quality in hundreds of ponds and lakes, restored many miles of rivers, and enhanced thousands of acres of ecosystems in the Northeast. From species surveys to water quality monitoring, our professionals perform comprehensive assessments in order to understand the landscape. Using tools like ArcGIS, we can map and model the watershed and arrive at holistic solutions for resource management. Our natural resources and lake management experts are complemented by our field team who utilize amphibious vehicles for mechanical invasive species removal, install aeration systems to improve water quality, and conduct natural lake treatments to manage algal blooms. We have secured millions of dollars in grant funding for watershed and ecological restoration projects on behalf of our clients.
Click here to learn about the Watershed Management Program in Somerset County, for which we recently helped secure grant funding from the New Jersey Highlands Water Protection and Planning Council.
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