DEP algal bloom advisory: updates and information

Current Advisory

9-13-2019 The DEP’s advisory remains in effect for all areas of the lake except Indian Harbor, Henderson Cove,
Byram Cove, Byram Bay to Halsey Island, and, as of 9/6, the area surrounding ST-14 (S.E. of State
Park beach) in the southern part of the lake.

On 8/8, 8/12 and 8/15, beaches in this area of the lake were sampled and results are included in the
tables below. As per the DEP/DOH Harmful Algal Bloom (HAB) Freshwater Recreational Response
Strategy, two subsequent samples below the health advisory guidance thresholds are required for
reopening of a regulated Public Recreational Bathing facility. Based on the data, DEP/DOH has
approved the local health department to re-open the following beaches: as of 8/13 Pebble Beach,
Sand Harbor, Bass Rock Beach, Sperry Springs Beach, Beck Lane Beach and CAPP Beach, and as of
8/16, Byram Bay Community Club Beach and Clearwater Beach.

The DEP urges the public to avoid swimming or water sports that may result in contact with the water,
such as water-skiing, tubing, canoeing, paddleboarding, and kayaking. There is no recommended
limitation on fishing or passive recreational boating that does not have the potential for splashing.
However, fish caught should not be eaten. The public is further advised that pets should not be allowed
in the water or to drink it.


The DEP is taking twice-weekly water samples of the lake and, along with the U.S. Geological Survey, has deployed real-time monitoring buoys to help assess when the lake is safe again for all recreation.

Testing results

For DEP testing results CLICK HERE.
Results will be updated each Wednesday and Friday (after Tuesday/Thursday testing and Wednesday aerial checks).

Real-time monitoring data

For DEP real-time monitoring data for Lake Hopatcong CLICK HERE. For USGS real-time data CLICK HERE.

Health concerns

On Friday, June 28, the Department of Health sent a LINCS (health alert) message to healthcare providers, hospital infection preventionists, and local health departments informing physicians to be aware and consider Harmful Algal Bloom (HAB) related illness in patients reporting swimming in or having contact with Lake Hopatcong. In addition, the New Jersey Communicable Disease Service (CDS) recently launched a waterborne illness web page where information related to HAB illness is provided. You can find the website here:

The Department of Health instructs residents to contact their healthcare provider if they believe they are experiencing symptoms from the HAB.

Algal bloom FAQ

For answers to the questions we have been most frequently asked, CLICK HERE

Summary of 7/22/2019 Special Lake Hopatcong Commission Meeting

Lake Hopatcong Commission holds a special meeting about HAB

Summary of 7/8/2019 Lake Hopatcong Commission Meeting

Packed house at LHC meeting to discuss harmful algal bloom

** UDATE 7-3-2019 **

Harmful algal bloom advisory for Lake Hopatcong remains in effect

** UDATE 7-2-2019 **

State Update: Advisory remains in effect, but conditions “somewhat improved”

** ALERT 6-27-2019 **

DEP advises public to avoid contact with Lake Hopatcong water due to harmful algal bloom

“Recreational exposure can occur while swimming, wading and during watersport activities such as jet skiing, kayaking, wind-surfing and paddle-boarding. The DEP is advising the public to avoid these activities and all contact with water from Lake Hopatcong until further notice. People also should not eat fish caught in the lake or allow pets to come in contact with lake water or drink the water.”


For more HAB-related resources, click HERE.


Categories: News, Other, Water Quality, water safety