Virginia Department of Health lifts harmful algae bloom advisory for Lake Anna

The Virginia Department of Health has lifted the harmful algae bloom advisory for Lake Anna due to the end of the recreational season.

The Upper North Anna Branch has experienced a HAB since June. In July, the advisory was extended to include the Middle North Anna Branch and the Upper and Middle Pamunkey Branches and Terry’s Run.

Results of samples collected Sept. 18 and Oct. 15 for Upper and Middle Pamunkey Branch indicated potentially toxic cyanobacteria were at acceptable levels allowing the advisory to be lifted.

To lift advisories, VDH needs two acceptable samples collected at least 10 days apart. While the Oct. 15 sample results from the Upper and Middle Pamunkey branches and Terry’s Run were at acceptable levels, the Sept. 18 sample results were at unsafe levels of cyanobacteria.

No additional sampling at Lake Anna is planned. The Virginia Harmful Algal Bloom Task Force suspends response sampling and any active HAB advisories at the end of October each year when the swimming season concludes and temperatures begin cooling in natural waters.

Algae blooms, which are still present in November in areas of a waterbody, may persist into late fall and possibly winter months. The public should avoid discolored water or scums that are green or bluish-green because they are more likely to contain toxins.

The Virginia Harmful Algal Bloom Task Force, which includes the VDH, the Virginia Department of Environmental Quality and the Old Dominion University Phytoplankton Laboratory, will resume response efforts in May 2025.

For more information, visit www.SwimHealthyVA.com.