2025 Monitoring Shows Very Good SML Water Quality
SMITH MOUNTAIN LAKE, VA –The SMLA Water Quality Monitoring program recently completed the final monitoring session for 2025. The overall results show very good water quality in Smith Mountain Lake
The monitoring this year produced results consistent with the 20-year averages for the three key parameters measured: water clarity, phosphorus, and chlorophyll-a.
Average water clarity at the 84 lake sites sampled was 1.86 meters, a slight improvement compared to the 20-year average of 1.83 meters. While it is typical to see water clarity decrease slightly as the summer progresses, it is a favorable sign that the latest result is in line with the 20-year average.
Average phosphorus concentration at the 56 lake sites sampled was 28.46 parts per billion, compared to the 20-year average of 24.49. Phosphorus is a polluting nutrient that can stimulate unwanted algae growth, so a lower number is preferable.
Actions that can help lower phosphorus concentration include avoiding lawn fertilizers containing phosphates, maintaining a shoreline buffer of vegetation that slows the runoff of rainwater and nutrients into the lake, and minimizing boat wake in shallow areas which can stir up sediment from the lake bottom.
Measurements of chlorophyll-a concentration in the lake were hampered this week due to a malfunction of the laboratory equipment used to perform this analysis. Prior to this week, the numbers were trending favorably compared to the 20-year average. Chlorophyll-a is an indicator of algae growth in the lake, so the decreasing trends seen in previous weeks were a favorable result.
Charts showing results for each of eight different sections of the lake as well as lakeside averages are posted at the SMLA website.
“We are very fortunate to have more than 50 volunteers who perform water sampling every two weeks during the summer and our partners at Ferrum College who perform the laboratory analysis of the collected samples. It is through their efforts that we have been able to accumulate extensive data over the past 39 years that informs us about the health of the lake,” says SMLA Director of Water Quality Monitoring, Tom Hardy.
SMLA volunteer Mark Earnhardt prepares to take a water clarity reading near the SML dam.
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.
