Mercer County Park and the New Jersey Department of Environmental Protection reported that there was a bloom of algae on Mercer Lake this past weekend (Aug 6-7, 2016). While this type of algae bloom can produce toxins that are dangerous to humans, the toxins in the algae bloom on Mercer Lake was below the levels that are considered harmful to humans. The initial bloom on the lake has subsided.
Mercer County Park and the NJDEP are monitoring the lake for additional algae blooms. At this point in time there are no reported blooms and the lake is open for general use. PNRA is in close communication with Mercer County Park and in event of a new bloom developing, we will take appropriate action which could include suspension of rowing activities.
Algae blooms occur in stagnant water near the shore of the lake. It is characterized by what looks like blue or green paint poured in or on the water. Not all blooms produce toxins that are harmful to humans or animals. Disturbing a bloom causes the toxins to be released and the toxins are local to the bloom. On Mercer Lake, the bloom was on the south side of the lake near the dam. There has been no algae bloom or activity reported on the rowing course in the middle of the lake or on the north side of the lake where the Caspersen Rowing Center is located.
More information on algae blooms can be found in the following flyer issued by the NJDEP which can be found here.