There are currently four Cyanotoxin harmful advisories in place for Lake Williston, Hunting Creek Lake, Masonville Dredged Material Containment facility (private) and Unicorn Fish Hatchery ponds (private).

Staff are tracking an additional 10 cyanobacteria blooms in Lake Williston (girl scout camp), Wye Mills pond and downstream creek, Lake Linganore, Smithville pond, Higgins Millpond (Transquaking), non-tidal Potomac River, Susquehanna Flats, Blackwater and little Blackwater Rivers, Poplar Island, Hart Miller Island.

• Red water in Pocomoke Sound caused by low levels of Margalefidinium polykrikoides, formerly Cochlodinium - water was red in color. 8/5/21
• Reddish-brown water in the Potomac River was Karlodinium (below bloom levels). 8/10/21
• Purple-streaked water in Tangier Sound caused by Prorocentrum scutellum. 8/16/21