Algae bloom reported in upper portions of Lake Anna

The first harmful algae bloom of 2020 in Lake Anna has been reported in the Upper Pamunkey branch, including Terry's Run, and the Upper North Anna branches. The affected areas can be seen on an interactive map at

The Virginia Department of Health issued an advisory on July 22 for people and pets to avoid contact with the water in these areas until algae concentrations return to acceptable levels. Advisory signs will be posted in areas of the lake.

Some harmful algae, called cyanobacteria, can cause skin rash and gastrointestinal illnesses, such as upset stomach, nausea, vomiting and diarrhea. 

The advisory stems from samples collected on July 15 during routine monitoring above New Bridge Road (Route 208).

The specific areas affected include:

Pamunkey Branch 

  • Upper – From the upper inundated waters of the Pamunkey arm of the lake downstream to the confluence with Terry’s Run
  • Terrys Run – from the upper inundated waters of the lake downstream to the confluence with Pamunkey Creek

North Anna Branch 

  • Upper – From the upper inundated waters of the North Anna arm of the lake downstream to the Route 522 Bridge.

According to the health department, algae blooms can occur when warm water and nutrients combine to make conditions favorable for algae growth. Most algae species are harmless. But some species may produce irritating compounds or toxins. VDH advises people to avoid discolored water or scums that are green or blueish-green because they are more likely to contain toxins.

In general, advisories will be lifted following two consecutive test results with acceptable levels for algal cell counts and/or toxin concentration.

VDH advises the following:

  • Do not allow children or pets to drink from natural bodies of water.
  • Keep children and pets out of the areas experiencing a harmful algae bloom and quickly wash them off with plenty of fresh, clean water after coming into contact with algae scum or bloom water.
  • If you or your animals experience symptoms after swimming in or near an algal bloom, seek medical/veterinarian care.
  • To ensure fish fillets are safe to eat, properly clean fish by removing skin and discarding all internal organs, and cooking fish to the proper temperature.
  • If you suspect you experienced health-related effects following exposure to a bloom, contact the Virginia Harmful Algal Bloom Hotline at 1-888-238-6154.
  • To learn more about harmful algae blooms or to report an algae bloom or fish kill visit


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