Posted: March 19, 2017
What is an algal bloom?
Algae are naturally-occurring microscopic organisms that are found in fresh and salt waters of Virginia and around the world. Algae species in fresh and salt water may multiply rapidly when environmental conditions are favorable for their development. The great number of algal cells in the water results in what is called an algal bloom. Sometimes the algae present aren’t actually algae at all, but rather are cyanobacteria, or ‘blue-green algae’. These organisms may also ‘bloom’ and some species have the ability to produce toxins. Algal blooms often result in a noticeable change in the color of the water. They can be many colors, but are most commonly green or reddish-brown. An odor may also be present in the vicinity of the bloom. Blooms are commonly seen in summer, but have appeared earlier, wider and more intense than in years past. This is likely due to a very warm summer and atypically warm winter.
How common are they?
Algal blooms are not uncommon in lakes and freshwater rivers, in spring and summer. Algae respond to the same conditions that encourage plant growth on land, and thus are most likely to form blooms when waters are warm and nutrient rich.
Where and what type of algal bloom is occurring now at John W. Flannagan Reservoir?
Officials do not believe any blooms are occurring as of 3/19/17 due to the cold temperatures which began about a week prior.
The USACE reported to the HAB Hotline on 2/28/17 that a potential HAB had been detected along the bottom of the reservoir, near the dam. USACE field staff detected the bloom through routine sampling and observations on 2/24/17.
Subsequently, the Virginia HAB Task Force and USACE have sampled and analyzed several samples within the reservoir, tributary rivers (Pound and Cranes Nest Rivers), as well as downstream of the dam along the Russell Fork River. Aphanizomenon flos-aquae, Raphidiopsis spp., Aphanizomenon klebhanii, and Chroococcus aphanocapsoides are species which have been detected in samples in early March – all at levels well below those which would pose a human health risk. From the last series of samples collected by staff on 3/9/17, results indicated that no harmful species were present and toxin test results were below detectable limits.
What is the risk to public health?
Most algae do not harm people, wildlife, or the environment. However, some types of algae in Virginia are dangerous and can affect fish and humans, as well as other animals like birds and mammals. These are known as Harmful Algal Blooms (HABs). Some species of cyanobacteria, or ‘blue-green algae’ can produce toxins harmful to humans and pets, fish, and wildlife when they reach ‘bloom’ levels of concentration.
If you are concerned that you have been exposed to a HAB, please see your doctor or call your local health department. Telling your doctor about contact with water and the specific location may help him/her treat any symptoms properly.
Are HABs dangerous my pets?
Rivers and lakes naturally contain bacteria and you should discourage pets from drinking untreated water. Water with a HAB is dangerous for pets, especially if they swim in or drink the water, because of the potential for toxins. If your pet is exposed to a HAB, wash the pet thoroughly with fresh water as grooming by licking could result in accidental ingestion of HAB toxins. Even a small amount of toxin may be deadly for a pet because of their small size.
Do HABs impact fishing?
It is safe to consume properly cooked fish fillets dressed from fish caught from waters with an algae bloom. Discard the carcass and guts and thoroughly wash skin and surfaces that come into contact with the fish.
What is being done to monitor the blooms?
Staff from local VDH, DEQ, and the water treatment plant will conduct weekly and or bi-weekly observations of Flannagan Reservoir as temperatures rise in the coming weeks. Observations will help in the detection of potential harmful algae blooms.
During a bloom event, samples are analyzed for harmful species and/or algal toxins to determine any risk to human health or shellfish. Several state partners are involved in regular monitoring for the presence of harmful algal blooms, including the Virginia Department of Environmental Quality, Virginia Department of Health Office of Drinking Water and Division of Environmental Epidemiology, Old Dominion University and other organizations – collectively known as the Virginia Harmful Algal Bloom Task Force. Results of the investigation at John W. Flannagan Reservoir are available on the Algal Bloom Map. Results of bloom investigations are posted on this map from March – November each year.
Citizen reports of illnesses suspected of resulting from primary recreational contact with water are analyzed for surveillance of potential harmful algal blooms.
What should I do if I see an algal bloom?
Contact Virginia’s toll-free Harmful Algal Bloom Hotline at (888) 238-6154
Avoid swimming in areas with a visible bloom, or water with unusual color or odor, or if dead fish are observed in the swimming area. When in doubt, stay out. If you come in contact with the bloom, wash skin thoroughly with fresh water. If you are concerned about HABs and your health, please see your doctor and call your local health department. Telling your doctor about contact with water and the specific location may help him/her treat any symptoms properly.