Reston Association advises caution after algae bloom spotted at Lake Audubon

Reston Association is monitoring a blue-green algae bloom that has emerged at Lake Audubon.

RA announced yesterday (Tuesday) that its watershed staff have found that the bloom contains the algal toxin microcystin, but tests of the water suggest the current levels of the toxin are low enough that no restrictions on recreation at the lake are necessary.

“However, environmental conditions such as increased heat or nutrients can affect levels and caution is advised,” RA said in the notice. “As always, no swimming is allowed at any time in Reston’s lakes and pet owners should check for floating blue-green algae before allowing pets in the water.”

The Environmental Protection Agency describes microcystin as “a potent liver toxin and possible human carcinogen.” It is the most widespread type of blue-green algae, also known as cyanobacteria, which may cause issues ranging from allergic reactions to gastroenteritis, liver and kidney failure or death, though cases of severe human health issues are relatively rare.

According to RA, algae blooms often appear when temperatures rise, but they usually occur later in the summer.

The National Oceanic and Atmospheric Administration reported on July 9 that June 2021 was the hottest June on record in the U.S., though temperatures were average for this time of year in the D.C. area.

While fishing and boating on Lake Audubon are still permitted, users should “be careful to avoid the water,” RA says.

RA recommends staying in or on watercraft at all times, avoiding contact with algae, and not drinking water from lakes. The association also discourages people from eating fish caught in lakes.

“RA will be monitoring the lake closely to see if the toxin levels increase or decrease and will adjust the status from caution, danger or clear accordingly,” RA said.

Algae blooms have been a recurring issue at Reston lakes, including at Lake Audubon, which had a small bloom last August.

A particularly large bloom that appeared in Lake Thoreau that same month prompted RA to commit to spending more money on lake management this year in order to take a more proactive approach.

In addition to posing a potential health risk when in high concentrations, algae blooms can be devastating to freshwater ecosystems, as they can block out sunlight, clog fish gills, and create oxygen dead zones where no aquatic life can survive. Scientists say human activities and climate change are leading to more common and more toxic blooms.

According to the Reston Association, there is no method of removing toxins from lakes, but people can help prevent the nutrients that produce algae blooms from entering the water.

“The public can help reduce the occurrence of blue-green algae blooms by preventing nutrients (nitrogen and phosphorus) from entering waterways through responsible use of lawn fertilizers, picking up pet waste, and controlling sediment erosion,” RA said in its statement.

Reston Association Watershed staff have been monitoring a blue-green algae bloom on Lake Audubon. For more details please the attached image.

Please send any questions or concerns to our Watershed team at [email protected]. pic.twitter.com/GE9ug77PPi

— Reston Association (@RestonOnline) July 20, 2021

Photo via Reston Association/Facebook