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Posted Thursday, June 25th, 2020

Response to Harmful Blooms that Devastated Lake Hopatcong’s Recreational Season and Related Businesses in 2019

The State Department of Environmental Protection has announced the launch of an enhanced Harmful Algal Bloom response strategy that includes an interactive mapping tool to help lake communities better protect public health and to keep the public informed about harmful blooms occurring in lakes across New Jersey. It complements a color-coded HAB alert index recently unveiled by the DEP

Comprehensive information on the harmful algal blooms, response strategy, alert index and mapping tool may be found at

Photo shows a closeup look of a harmful algal bloom

Photo shows a closeup look of a harmful algal bloom

You can use the mapping tool from phones or personal computers to report suspected blooms, which the DEP will investigate. Residents also can view HAB testing data, local alert conditions and other important information about impacted water bodies.

DEP Commissioner Catherine McCabe said the mapping tool and health alert index should improve the flow of information that is essential to safeguard public health, the environment and local economies that depend on recreation and tourism.

Harmful algal blooms devastated lake communities, such as Lake Hopatcong, stopping some recreational activity and crippling local economies dependent on lake recreation.

DEP’s HAB Interactive Mapping Tool and Response Strategy

Users of the mapping tool can provide the DEP with GPS coordinates and photos of potential blooms. The DEP will investigate the report to determine if a bloom is occurring and needs to be monitored. Monitoring results will be posted for each impacted water body as they become available.

The mapping tool also provides a location and monitoring data for each bloom reported to the DEP. This level of detail was available only for Lake Hopatcong and Greenwood Lake last year.

It also details enhanced monitoring techniques through use of field pigment meters, continuous-monitoring buoys, aircraft remote-sensing, unmanned aerial vehicles, and satellite imagery, to complement traditional water sampling.

HAB Initiative and the DEP Alert Index

The response strategy is part of a broader HAB initiative directed by Gov. Murphy in 2019 to address economic, environmental and public health impacts of harmful blooms that occurred statewide last year. This initiative also includes more than $13 million in funding for local projects to mitigate and reduce impacts of these blooms.

Last month, the DEP released a HAB alert index (see below), a tiered information and signage system that provides guidance on suitable recreational activities in impacted water, depending on levels of bacteria and/or cyanotoxins. When harmful blooms occur, color-coded signs will be posted to provide current conditions and recommendations on recreational activities.

DEP Launches Algal Bloom Map and Strategy for Lake Hopatcong and Other Lake Communities

The index makes it clear to the public that, in some instances, boating and related activities may still be suitable when lower levels of harmful algal blooms are detected. Signage for each of these tiers has been developed and is available for download from the DEP’s HAB website at

About Harmful Algal Blooms

Harmful algal blooms are not caused by true algae but by cyanobacteria that in many ways mimics algae. Cyanobacteria naturally occur in fresh water and can proliferate to unhealthful levels in sunlight and hot weather, forming dense mats resembling pea soup.

Exposure to cyanobacteria can cause a range of mild-to-moderate health effects, including rashes, allergy-like reactions, flu-like symptoms, gastroenteritis, respiratory irritation and eye irritation.