LOUISA COUNTY, Va. (WRIC) -- The Virginia Department of Health (VDH) has lifted the swimming advisory placed on Lake Anna over the summer -- put in place as harmful algae blooms were detected in the water -- because the recreational swimming season is over. However, such algae blooms could still be present. On Thursday, Nov. 7, the VDH announced that the harmful algae bloom (HAB) advisory in place across Lake Anna's Upper and Middle North Anna branches, Upper and Middle Pamunkey Branches and Terry's Run since July has been lifted. Such harmful algae blooms are known to cause skin rash and gastrointestinal illness. To prevent this harm, the VDH issued this HAB advisory, urging the public to avoid contact with water in the affected areas of Lake Anna. "Results of samples collected September 18 and October 15 for Upper and Middle Pamunkey Branch indicated potentially toxic cyanobacteria were at acceptable levels allowing the advisory to be lifted," the VDH said. VDH policy dictates that, in order to lift an advisory, two water samples with acceptable levels at least 10 days apart must be collected. "While the October 15 sample results from the Upper and Middle Pamunkey branches and Terry’s Run were at acceptable levels, the September 18 sample results were at unsafe levels of cyanobacteria," the VDH said. "No additional sampling is planned." Algae blooms of this nature can still be found in waterbodies in November and they may persist into late fall or even winter, according to the VDH. "The Virginia Harmful Algal Bloom Task Force suspends response sampling and any active HAB advisories at the end of October each year when the recreational (swimming) season concludes and temperatures begin cooling in natural waters," the VDH said. That task force is made up of the VDH, the Virginia Department of Environmental Quality and the Old Dominion University Phytoplankton Laboratory. According to the VDH, it will "resume response efforts in May 2025, weather permitting." The VDH advised that the public should still "avoid discolored water or scums that are green or bluish-green because they are more likely to contain toxins."