The New Jersey Department of Environmental Protection (DEP) is advising the public to avoid swimming in or contact with the waters of Lake Hopatcong (New Jersey’s largest lake — straddled by Sussex, Passaic and Morris counties) due to an extensive harmful algal bloom (HAB).
Using aerial surveillance, The DEP’s Division of Water Monitoring and Standards confirmed that large areas of the lake are experiencing cyanobacteria blooms.
Cyanobacteria are naturally present in lakes and streams in low numbers. Under the environmental conditions of sunlight, high nutrients, warm temperatures and calm water, dense cyanobacterial blooms can form. 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.
Based on the widespread nature of the HAB, the recreational advisory may be in place for weeks, if not longer. As a precaution, the DEP is recommending that all public swimming beaches along the lake be closed.
Exposure can cause a range of health effects, including rashes, allergy-like reactions, flu-like symptoms, gastroenteritis, respiratory irritation, skin rashes and eye irritation.
- 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 lake
- 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), or send a mobile alert via the WARN NJDEP mobile app (available at iTunes and Google Play). Or visit the NJDEP HAB website.
More information about cyanobacterial HABs, what to do if people or pets are exposed; links to the federal Environmental Protection Agency and Centers for Disease Control; a gallery of HAB and non-HAB photos; and other resources are available at the New Jersey HAB Web site.
The DEP will monitor cyanobacteria levels until the lake is determined to be safe for recreational contact.