Skip to Main Content

August 8, 2003
Bluegreen Algal Blooms observed in Northeast River, Bohemia River of the Upper Chesapeake Bay.

Water samples collected by Maryland Department of Natural Resources field staff from the Northeast and Bohemia Rivers on August 7th during routine water quality monitoring on Chesapeake Bay showed bloom levels of blue-green algae. The Bohemia River sample was dominated by Microcystis aeruginosa at 121,214 cells/ml. The algal concentrations at the Northeast River contained Microcystis at 30,705 cells/ml with other blue-green algae, Anabaena at 48,760 cells/ml and a presence of Aphanizomenon.

Microcystis, Anabaena and Aphanizomenon may contain toxins that can cause health problems in humans and animals that come in contact with or drink the water. Maryland Department of Natural Resources collected samples of blue-green algae from the Sassafras River on July 22, 2003 and have submitted them to laboratories for analysis of toxin content. Results are expected in two to three weeks (see HAB News from August 7, 2003: "Betterton Beach (Sassafras River, Chesapeake Bay) closed due to bluegreen algal bloom."). In hot weather, and especially in still water with high levels of nutrients, blue-green algae can grow and accumulate rapidly, causing a bloom. Cases of human illness this year have included itching and rashes from contact with bloom waters, people should take common precautions to reduce the risk of illness or discomfort related to blue-green algal blooms:

  • The public should not swim in areas where blue-green algae bloom is evident. Do not drink water from any area with the appearance of a blue-green algae bloom.
  • If contact is made with problem water, simply wash off with fresh water. In some cases, skin irritations may occur after prolonged contact. If irritations persist, see a physician or local health care provider.
  • Keep pets and livestock away from bloom areas. Blue-green algal blooms may contain toxins that could be harmful or fatal to pets and livestock.

Blue-green algae naturally occur in tidal freshwater portions of the Chesapeake Bay and its tributaries. However, algal blooms may periodically use up oxygen, causing fish to suffocate and die. Affected waters may also appear as if a blue-green to yellow-green paint is floating on the surface of the water. Major blue-green algae blooms were last reported in the upper Bay region in 2000.

A Press Release regarding conditions on the Sassafras River was published by Maryland Department of the Environment July 22nd and may be referenced for further information on blue-green algal blooms in the upper Chesapeake Bay. A fact sheet on Microcystis and the 2000 bloom can be found on the Department of Natural Resources’ website at: www.dnr.state.md.us/bay/hab/microcystis2.html. Maryland Departments of Natural Resources and Environment will continue to monitor the situation and publish updates to the website as necessary. To report a fish kill or fish health related event, please call the Fish Health Hotline at (888) 584-3110, 24 hours a day.