ROXBURY, NJ - The green slime that has shut-down Lake Hopatcong for swimming and other water activities is the largest in state history and it might stick around all summer, said officials from the state Friday.

The "harmful algal bloom," known as an HAB, is covering about 30 percent of the water body with a "mat of pea colored bloom," said Bruce Friedman, director of water monitoring and standards in the state Department of Environmental Protection (DEP).

He said biologists have never seen anything like it. HABs are not uncommon, but generally are limited to smaller areas, such as coves, he said.

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"This is the first harmful algal bloom of this magnitude in New Jersey," Friedman told reporters during a conference call. "We've never seen an HAB that covers the majority fo a New Jersey lake."

The green slime contains toxins that can cause illnesses including skin rashes and digestive sickness. Over long periods of ingestion, they can even be carcinogenic, said the DEP.

The state is advising people to steer clear of even coming into contact with Lake Hopatcong water and to keep their pets away as well. Drinking Lake Hopatcong water or using it for cooking is illegal to begin with, butpeople still do it, Friedman lamented. He said the HAB makes that practice particularly dangerous.

While beaches are open, swimming at most has been banned.

Boaters Better Be Smart

Boating has not been prohibited, and tonight's fireworks display -  where thousands gather to watch on boats, beaches and docks - is still scheduled to take place as is tomorrow's Miss Lotta Veteran's Cruise.

However, Friedman said boaters should use common sense; cruising fast enough to cause a spray of water into the boat would be a bad idea. "You should avoid activities  that include direct contact with water in Lake Hopatcing," he stressed.

Similarly, while fishing is still allowed, anglers should wash their hands with clean water after they remove their catches from the water, the DEP said. And they should definitely throw back the fish as eating them could induce sickness.

The DEP said State Police will be patrolling the lake mainly to warm people who might be involved in risky activities. The officials said the state is not treating that behavior as any type of crime and said the police "will let people know that what they are doing is not a good idea."

The lake has been experiencing blooms of "cyanobacterial harmful algal blooms" (CyanoHABs) in various areas since first being reported in Byram Cove on June 17, Friedman said. As of today, the DEP has received about 30 HAB individual HAB reports.

Flyovers to Continue

The state has flown several surveillance flights over the lake and plans to do more. From the aircraft, biologists use a multispectral sensor that allows them to analyze the pigment of the material and determine if it's an HAB, Friedman explained.

CyanoHABs are naturally present in lakes and streams, usually in low numbers, according to the DEP. However some conditions cause dense blooms which produce floating mats on the water surface, according to the state.

"The rapid spread of the bloom may be the result of heavy rainfall carrying nutrient-laden stormwater into the lake, followed by periods of warm weather," it theorized on the DEP website. "Based on the widespread nature of the HAB, the recreational advisory may be in place for weeks, if not longer. The duration of a Harmful Algal Bloom is unpredictable and may be influenced by availability of nutrients and weather conditions. In many cases in 2018, HAB was observed on water bodies well into the fall season."