What happens when a bloom is suspected?

When a citizen, SMLA volunteer, or Ferrum College researcher notices visual conditions that may be suspicious, a report can be filed with the VDH, which will trigger a response protocol.

VDH will send the Virginia Department of Environmental Quality (VDEQ) to collect water quality samples for analysis at a state certified lab to analyze the water sample for the presence of toxins. If elevated levels of toxins are present, the VDH recommends the placement of a Swimming Advisory on the affected portion of the waterbody.

What is a Virginia Department of Health Swimming Advisory?

In 2023, the Blackwater arm of Smith Mountain Lake was placed under a Swimming Advisory by the VDH which began on June 6th and lasted until August 24. VDH determined that a Swimming Advisory for the entire Blackwater arm was warranted because three samples taken by DEQ in early June showed elevated concentrations of cyanobacteria above the advisory level. None of the samples contained toxins anywhere near the advisory threshold, although toxins were present.

A VDH Swimming Advisory does not mean the lake is “closed”. The reason for implementing a Swimming Advisory is to inform the public that a health risk might be present, based on sampling results. At the time a water sample is collected, either concentrations of cyanobacteria and/or toxins are found to exceed the established thresholds.

A Swimming Advisory recommends staying out of water that is discolored, has a visible scum, and/or has an odor. Bathing after contact with the water is highly recommended. Drinking the lake water is never recommended. Non-contact recreation such as boating, kayaking, fishing, and sports that don’t lead to submersion of your head in the water, are recommended as safe alternatives during a Swimming Advisory.

Recreation can continue in the water, but awareness of the risks is important. It is up to you to make the choice to swim, or not, based on the information that VDH provides in the Swimming Advisory. SMLA always advocates that if the water looks or smells unusual, when in doubt, stay out.

How does a Swimming Advisory end?

Only the VDH can end a Swimming Advisory based upon resampling, two times, and both samples must show that no thresholds are exceeded. The sampling events must be a minimum of ten days (10) apart.  If the first return sampling event still shows elevated concentrations and/or toxins, the clock starts over, meaning another 10 days must pass before resampling.

What do you do if you see something that might be a HAB?

If you notice conditions in the lake that look anything like following pictures of HABs, and you are pretty sure it’s not pollen or plants, you can file a citizen report with the VDH on their HAB portal. You will need to provide your street address, contact information, and importantly, a photo, latitude, and longitude of where you saw the suspect water conditions. You can get that from Google maps.

We also encourage you to notify SMLA, via email to lqcchair@smlassociation.org, to report the conditions to us as well.

When the VDH receives a citizen report, they often reach out to Ferrum College and the Smith Mountain Lake Association to see if those groups can get a sample and look at it under a microscope. If citizen photos and Ferrum/SMLA feedback cannot rule out a HAB, VDH will trigger the VDEQ to respond and collect an official sample for analysis of cyanobacteria concentration and toxicity.

If you file a report, you may be contacted to allow VDEQ personnel onto your property to collect a sample at your dock or shoreline location. The sample team may come by boat, and not need property access. The VDH will follow up directly with the citizen posting the report with testing results, although results may take up to two weeks to receive.

What happened at SML in 2023?

What happened in 2023 to produce widespread long-lasting HABs? Why have we never had a Swimming Advisory before? Will it come back?

While we still don’t know exactly why the summer of 2023 was seemingly so different from other summers, we do know the triggers for harmful algal blooms are an overabundance of cyanobacteria, excess nutrients in the water and warm, sunny weather.

The lake has had and still has concentrations of nutrients, especially phosphorus, that are relatively high compared to other bodies of water. Although the lake wide average of phosphorus has remained relatively constant for the past number of years, upper reaches of the lake, like up the Blackwater and Roanoke have higher levels than areas down near the dam.

Phosphorus and other nutrients are introduced into the lake through runoff and stormwater. Sources of these nutrients include lawn and agricultural fertilizers, livestock, pet, and wildlife waste, leaking or malfunctioning septic systems, and erosion/siltation. Nutrients can also be found in the lake bottom. Sunken leaves, brush, and dissolved organic material all release nutrients as they decompose. Streams feeding into the lake have been found to contain elevated phosphorus levels as well.

What is being done?

How do we start to understand this complicated puzzle? The first step is to assess the condition of the watershed surrounding the lake. What percentage of the watershed is forest, farm, houses, and impervious cover? How many septic systems are within 100 feet of the lake edge? What kind of rainfall and runoff comes into the lake? How do streams and other flow characteristics affect the surface water of the lake?

To start getting some answers, SMLA worked with a professional lake management and engineering firm to to assess the watershed condition of the Blackwater arm of SML. To enhance this study, sediment and surface water samples were taken at the sites of the 2023 HABs in the Blackwater were analyzed to see if cyanobacteria survive the winter in a dormant state and are ready to go as soon as the weather warms up.

A group of volunteers organized by SMLA collects samples at docks. Organized through the NOAA Phytoplankton Monitoring Network, the SMLA Dock Watch program monitors 20 dock locations around the lake. Volunteers have been trained by NOAA scientists to identify the most common cyanobacteria at the lake with microscopes. This program will help establish trends as well as keep an eye out for emerging conditions which could evolve into HABs.

And last, but not least the Ferrum College SML Water Quality Monitoring Program has operated for 35+ years with over 50 volunteers participating from SMLA. Out on the lake weekly between the end of May and early August, these volunteers and researchers are trained to watch for conditions that might be suspicious while conducting their regular sampling.