An algal sample was collected Thursday, November 6th, by MDE Shellfish Compliance personnel from Breton Bay (St. Mary's County) east of Protestant Point on the Potomac River. The water was noticeably reddish-brown. It contained Prorocentrum minimum at 110,800 cells/ml. Prorocentrum minimum is a potentially toxic dinoflagellate and typically the dominant spring blooming species in Maryland’s Chesapeake Bay. There are, however, periodic blooms of Prorocentrum in other seasons. Bloom levels of concern for possible living resource effects can begin around 3000 cells/ml.