Latest Smith Mountain Lake Water Quality Data Continues Positive Trend
SMITH MOUNTAIN LAKE, VA – Smith Mountain Lake average water quality continues to be good, consistent with the corresponding 20-year averages for the parameters measured. This according to the most recent data collected by the Smith Mountain Lake Association (SMLA) Water Quality Monitoring Program.
The highest water quality is typically found in areas farthest downstream such as those closest to the dam, and lower water quality is found in the uppermost sections of the lake. This reflects how nutrients and sediment flow into the lake from streams and the surrounding watershed which eventually settle out of the water as it flows downstream toward the dam.
“It is encouraging to see the high quality of the water being maintained in Smith Mountain Lake, offering plenty of recreational opportunities for families to escape the hot weather this summer,” said SMLA Director of Water Quality Monitoring Tom Hardy.
Highlights of the fifth bi-weekly monitoring session for 2025 include:
- Average water clarity at the 84 sites sampled was 1.92 meters, a slight decline compared to the 20-year average of 2.01 meters. It is typical to see water clarity decrease slightly as the summer progresses, often the result of warmer water stimulating increased algae growth and the cumulative effect of increased summer boat traffic stirring up sediment.
- Average chlorophyll-a concentration at the 56 sites sampled was 4.49 parts per billion, compared to the 20-year average of 7.30. Chlorophyll-a is an indicator of algae growth in the lake, so the lower number is a more favorable result.
- Average phosphorus concentration at the 56 sites sampled was 23.45 parts per billion, compared to the 20-year average of 25.39. Phosphorus is a polluting nutrient that can stimulate unwanted algae growth, so the lower number is more favorable.
Complete sampling results, including charts showing data by section of the lake, are posted at the SMLA website.
The SMLA Water Quality Monitoring Program is a partnership between SMLA and Ferrum College. The monitoring program was established in 1987 and is now in its 39th consecutive year. Roughly 50 citizen volunteers collect samples on the lake every two weeks in the summer, and the samples are analyzed by a team of student interns and environmental science professors at Ferrum College.
About SMLA
The Smith Mountain Lake Association (SMLA) mission is to keep Smith Mountain Lake clean and safe. Established in 1969, SMLA is the longest serving advocate for the SML community. Activities help to retain the pristine beauty of Smith Mountain Lake and the vibrant local economy. SMLA is a nonprofit 501(c)(3), volunteer-led organization that relies on memberships, donations and grants to support programs that protect SML.
