Residents are at moderate risk for health problems at Crescent Cove in Lake Hopatcong, where officials say a skin rash can occur from direct contact with bacteria.
Samples were taken from the two areas earlier this month.
If ingested, officials say the toxins can cause abdominal pain, headaches and sore throats.
Algae tends to bloom in the summer months when water temperatures are warmer than usual.
In 2019, the New Jersey Department of Environmental Protection had issued a warning for Lake Hopatcong because of a harmful algae bloom that had taken over the body of water.
Using highly specialized sensors, the DEP's Division of Water Monitoring and Standards' aerial surveillance confirmed that large areas of the lake was experiencing cyanobacteria blooms.
Often referred to as blue-green algae, cyanobacteria are not true algae but are capable of excessive growth through photosynthesis. Cyanobacteria blooms are usually a bright green, but can also appear as spilled paint, "pea soup," or as having a thick coating or "mat" on the surface. These blooms can often be confused for typical algae blooms.
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. The DEP will monitor cyanobacteria levels until the lake is determined to be safe for recreational contact.
In recent years, the DEP and the New Jersey Department of Health have been enhancing Harmful Algal Bloom surveillance and response efforts across the state.
In 2017, the DEP launched a campaign to educate the public about these blooms and provide resources on how to report them to the DEP. The "Avoid It and Report It" campaign advises the public to take the following steps when a suspicious bloom is observed:
--Avoid contact with water in the vicinity of the bloom, especially in areas where the bloom is dense and forms scum;
--Do not drink or consume the water
--Do not eat fish from the waterbody
--Keep pets and livestock away from the water
-Do not allow animals to drink the water, eat dried algae, or groom themselves after coming into contact with the water
--People, pets and livestock that come into contact with a bloom should rinse off with fresh water as soon as possible
--Seek medical attention or a veterinarian if a person or animal is experiencing adverse health effects after exposure to a bloom
--Report a suspected HAB by calling the DEP Hotline at 1-877-WARNDEP (877-927-6337) send a mobile alert through the WARN NJDEP mobile app (available via iTunes, Google Play or Windows Phone) or report via the DEP's HAB website.
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