Maryland Department of Natural Resources encountered blue-green algal bloom conditions continuing on the Potomac River during routine water quality monitoring on September 15th. Microcystis cell counts declined at Smith Point from over 2 million cells/ml on September 2nd (see HAB News from September 4, 2003: "Middle Potomac River conditions ripe with blue-green algal bloom.") to 1.64 million cells/ml. Blue-green algae dominated by Microcystis were evident from Indian Head to Maryland Point. Mattawoman Creek was the second most affected site with Microcystis concentrations of 25,864 cells/ml and the addition of Anabaena and Aphanizomenon common to the sample.

Hurricane Isabel is expected to reach Maryland on Thursday, September 18th and continue through Friday, September 19th. The storm surge is presently predicted to reach the Smith Point area on the Potomac River. Coupled with significant rain and runoff, habitat conditions including salinity, turbidity, flow and temperature are expected to change dramatically and will impact the distribution and abundance of this algal bloom as well as other living resources. The effects of the storm on Chesapeake and Coastal Bays water quality can be tracked using continuous water quality monitoring results, habitat mapping and long-term water quality monitoring data presented on Maryland DNR's Eyes on the Bay website.

The Maryland Department of Natural Resources will continue to monitor all Microcystis blooms throughout the state. For up to date information on all of Maryland's harmful algal blooms and water quality, please visit Eyes on the Bay.