Public reports have declined for the spring algal bloom of Prorocentrum minimum that caused widespread accounts of Mahogany Tide in Chesapeake Bay and its tributaries during the month of May. Recent water samples collected by Maryland DNR in areas that were hot spots for Mahogany Tide before the Memorial Day weekend (e.g., Rockhold Creek and Glebe Creek and Bay in Anne Arundel County) have a lot of color in the water but relatively low concentrations of the bloom-causing dinoflagellate. Significant rain events occurred over the Memorial Day weekend and have continued into early June enhancing runoff into the Bay and its tributaries. At the peak of the Mahogany Tide this season, the extent of the bloom during May reached north into the area of the Bay Bridge and south into the Patuxent and Choptank Rivers on the western and eastern shores respectively.

Phytoplankton monitoring is conducted throughout the year in the Coastal and Chesapeake Bays and their tributaries. Please continue to visit Eyes on the Bay as well as the Harmful Algal Blooms website throughout the year as Maryland DNR will provide updates on any new harmful algal bloom events.