Didymo was found in early 2008 in Gunpowder Falls below Prettyboy Reservoir in Baltimore County. Since July 2008, DNR and Baltimore County/DEPRM have been monitoring Didymo occurrence monthly in the Gunpowder Falls between Prettyboy and Loch Raven reservoirs.
Below are maps containing Didymo locations and survey sites by month.
580 Taylor Ave., Annapolis MD 21401
Call toll-free in *Maryland* at 1-877-620-8DNR (8367)
Out of State: 410-260-8DNR (8367)