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Posted Tuesday, October 29th, 2019

The state Department of Environmental protection reports that recreational water use restrictions, due to a harmful algal bloom, have been lifted for Prospect Point and Woodport Bay areas in the northeastern portion of the lake.Lake Hopatcong Algal Bloom -- Advisory Lifted for Prospect Point and Woodport

However, additional sampling conducted outside of those areas due to observations of localized suspected algal blooms found that three locations showed cell counts greater than the health advisory guidance level.  As a result, advisories continue in effect for the shoreline at Byram Cove, and now for Pine Tree Point and the area north of Bertrand Island.

Recreational users are reminded to avoid swimming or coming in contact with lake water in these twp remaining areas until monitoring demonstrates that cell counts fall below the Health Advisory Guidance level.

For more information on state DEP sampling and findings, please see  and

Harmful algal blooms are caused by bacteria that in many ways resemble and behave like algae. The causes of the Lake Hopatcong bloom this summer and fall are not fully understood. However, harmful algal blooms are generally fueled by nutrient-laden stormwater runoff followed by periods of hot weather that cause the proliferation of these bacteria, which are naturally present in waterbodies.

Under these conditions, blooms can reach levels that can be harmful to people and to pets coming in contact with the water. They typically subside with the onset of cooler weather.

If suspected algal blooms are observed, the DEP asks residents to please report it calling the DEP Hotline (1-877-WARNDEP (927-6337) or via the Warn DEP mobile app.
All previous results (6/10/19 – 10/10/19) for Lake Hopatcong sampling stations are available here.

For more information please see the updated HABS webpage  as well as the BFBM CyanoHABs Events webpage.