Advisory Issued for Flannagan Reservoir in Dickenson County Due to Algae Bloom

August 9, 2019

Media Contact: Robert Parker, public information officer, Western Region, 540-580-2960,

(RICHMOND, Va.) – The Virginia Department of Health has issued a health advisory for the lower (eastern) areas of John W. Flannagan Reservoir in Dickenson County due to a bloom of harmful algae. People and pets should avoid swimming, wading or bathing in these affected areas of the lake until algae concentrations return to acceptable levels. This includes windsurfing and stand-up-paddle-boarding; any activities which pose a risk of skin contact or accidentally ingesting the water.

The reservoir also serves as the raw water source for the John Flannagan Water Authority, which provides public drinking water to Dickenson and Buchanan counties and parts of Wise and Tazewell counties, serving some 37,000 customers. Since the bloom was discovered, the Authority has adjusted the treatment protocol and increased monitoring. VDH has observed no evidence of impacts to drinking water at this time.

The 1,143-acre reservoir, formed by a dam on the Cranesnest and Pound Rivers, is a popular local recreation area for boating, swimming and fishing, with public access at five boat ramps, three campgrounds, two fishing piers and a marina.

Signs will be posted at the shoreline in affected areas. The signs read, in part: “WARNING: Harmful Algae Present. People and animals should avoid swimming and wading until further notice. Exposure to algal toxins may cause illness. … While fish consumption is not affected, thoroughly cleaning the fish, discarding the carcass and guts, and washing hands and surfaces afterward with soapy water is advised.”

The affected areas — below Lower Twin Branch to the dam, including Skeetrock Branch — are illustrated on an interactive map at

Some harmful algae, called cyanobacteria, can cause skin rash and gastrointestinal illnesses, such as upset stomach, nausea, vomiting and diarrhea. Everyone should take the following steps to prevent illness:

  • Avoid contact with any area of the lake where water is green or an advisory sign is posted. WHEN IN DOUBT, STAY OUT!
  • Do not allow people or pets to drink from natural bodies of water.
  • Keep people and pets out of the areas experiencing a harmful algae bloom. Wash 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

Algae blooms can occur when warm water and nutrients combine to make conditions favorable for algae growth. Most algae species are harmless; however, some species may produce irritating compounds or toxins. Avoid discolored water or scums that are green or blueish-green because they are more likely to contain toxins.

Routine monitoring occurs monthly with Flannagan Reservoir. Test results indicate samples collected Wednesday, July 31 near the dam and boat ramp of the lower reservoir contained potentially harmful algae (cyanobacteria) which exceeded safe swimming levels.

Additional sampling was collected Wednesday, August 7 to further establish the extent of the bloom. This advisory will be updated when test results are available, usually about a week later.

The Virginia Department of Health and the Virginia Harmful Algal Bloom Task Force, which includes the Virginia Department of Health, Virginia Department of Environmental Quality and the Old Dominion Phytoplankton Lab monitor water quality in the lake.

In general, advisories may be lifted following two consecutive test results with acceptable levels for algal cell counts and/or toxin concentration. An advisory may be lifted or maintained at the discretion of the health department. For example, after one test an advisory may be lifted if results are below safe levels for swimming, if other information indicates exposure or human health risk is low.

For more information visit or see the Advisory Report at .