High cyanobacteria levels detected in Monmouth County reservoir

Yet another body of water has tested positive for high levels of cyanobacteria.

A harmful algal bloom has been detected at the Manasquan Reservoir in Howell Township with levels of cyanobacteria above the state threshold of 20,000 cells per milliliter.

While residents should avoid contact with the water at the reservoir, officials say the bacteria does not pose a risk to the roughly 300,000 Monmouth and Ocean County residents who get their drinking water from the reservoir.

Ken Klipstein is the director of watershed protection programs at the New Jersey Water Supply Authority, which manages the reservoir. He says the water treatment process is designed to remove cyanobacteria from drinking water. But if the bacteria levels rise, the reservoir itself may need to be treated with an algaecide.

“We are monitoring numbers carefully to see if we need do that now,” said Klipstein. “Sometimes counts get so high, it’s difficult for the treatment plant itself to take it out, so we have to do some treatment to the source water.”

The Monmouth County Parks System is urging residents to avoid contact with the water, not to eat fish caught in the reservoir, and to keep pets and livestock from drinking or coming in contact with the water. Boat rentals have also been suspended.

The reservoir adds to an ever-growing list of locations where officials warn contact with the blooms puts swimmers at risk of rashes, eye irritation, abdominal pain, nausea and vomiting.

Exposure to a bloom that is actively producing cyanotoxins could cause more serious including liver toxicity and neurological effects. A bloom could begin to produce cyanotoxins at any time, according to the DEP.

On Monday, the detection of an algal bloom prompted officials to close the beach at Budd Lake in Mount Olive. Residents are discouraged from swimming in nearby Lake Musconetcong as well.

Most of Lake Hopatcong has been closed to swimming since mid-June, but a third portion of the lake’s northwest corner — Byram Cove — reopened Thursday.

The New Jersey side of Greenwood Lake remains under a swimming advisory, while the New York side of the lake remains open to swimming and other recreation.

Rosedale Lake in Pennington and Spruce Run Recreation Area in Hunterdon County also remain under advisories.