On Tuesday 2/26/2002, Maryland Department of the Environment conducted algal sampling on the Potomac River. Maryland Department of Natural Resources processed the samples for identification of the algae. Additional algal samples were collected for toxicity testing by the U.S. Food and Drug Administration.

Concentrations of Dinophysis accuminata remained high but had declined from last week at the 301 Bridge, Swan Point and on the Wicomico River. Densities were consistently greater in the bottom of the water column (between 14,000 and 25,000 cells/Liter) versus near the surface (between 10,000 and 14,000 cells/Liter.

The temporary closure of the Potomac River shellfish waters has remained in effect.

Dinophysis tends to be found in higher salinity waters. The persistent drought conditions have resulted in higher salinity waters reaching farther up into the tributaries this winter than most years. Since 1985, record high salinity levels above 18 ppt are being observed in the vicinity of the Dinophysis concentrations.