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On July 9, USGS scientists deployed an advanced monitoring buoy to study water-quality conditions and a harmful algal bloom-HAB-recently detected in Lake Hopatcong, New Jersey. 

Scientists setting out a monitor for algal bloom
USGS scientists Lisa Carper and Jon Cohl deploy a monitoring buoy at Lake Hopatcong, New Jersey, to monitor water-quality conditions and a harmful algal bloom in near real-time.

USGS scientists from the New Jersey and New York Water Science Centers deployed an advanced monitoring buoy this week on Lake Hopatcong, New Jersey’s largest lake and a popular tourist and vacation destination, to assist the NJ  Department of Environmental Protection (NJDEP) in monitoring an active Cyanobacterial Harmful Algal Bloom (CyanoHAB). The USGS monitoring buoy will provide near real-time data on this bloom and its severity as well as a better understanding overall of CyanoHAB development, duration and decline on the lake.


The NJDEP Bureau of Freshwater and Biological Monitoring confirmed a CyanoHAB on Lake Hopatcong by aerial surveillance in late June.  Historically, the NJDEP has confirmed CyanoHAB events on many NJ lakes but none as extensive as this recent one on Lake Hopatcong. The state has issued advisories recommending the public avoid swimming in or contact with the lake’s water.


CyanoHABs are of increasing concern as they pose a threat to human and aquatic ecosystem health and cause economic damages. CyanoHABs can have severe impacts on  drinking-water supplies, aquatic ecosystem health, and safe recreational uses of freshwater resources in New Jersey. Cyanotoxins produced by some species of cyanobacteria can cause acute and chronic illnesses in humans and pets. Despite advances in scientific understanding of cyanobacteria and other associated compounds found in these types of blooms, many unanswered questions remain about occurrence, environmental triggers for toxicity, and the ability to predict the timing, duration, and toxicity of CyanoHABs. 

Harmful Algal Bloom floating on Lake Hopatcong
Harmful Algal Bloom on Lake Hopatcong.


This monitoring effort will provide a better understanding of CyanoHAB growth and severity and allow for near instantaneous detection of changing water-quality conditions. The USGS monitoring system includes a buoy equipped with real-time water-quality sensors to measure algae, accessory pigments produced by cyanobacteria, and organic matter in addition to routine water-quality constituents such as water temperature, specific conductance, dissolved oxygen, pH, and turbidity.  Water samples for the analysis of chlorophyll, accessory pigments produced by cyanobacteria, and carbon are being collected on a regular basis to validate sensor readings. In addition, routine sampling is being conducted to examine nutrient concentrations, changes in algal assemblages, presence of cyanotoxin-producing bacteria through genetic analysis, and cyanotoxin concentrations. This effort will help develop an understanding of algal bloom dynamics and the triggers associated with toxin production.


 A user-friendly data viewer allows resource managers and the public to view and explore lake conditions in near-real time. The dashboard also provides easy access to the discrete water-quality data available online through the USGS National Water Information System (NWIS) Website. 


The information from the monitoring buoy can help state officials, water resource managers, residents and tourists to make more informed decisions on how to deal with this bloom and develop mitigation strategies. Resulting data will also help officials distribute advisories on recreational lake activities  in a timely manner to protect human health. This USGS monitoring effort is being done in support of NJDEP’s Cyanobacterial Harmful Algal Bloom (HAB) Freshwater Recreational Response Strategy.

Scientists collecting samples on lake Hopatcong
USGS scientists Brad Bjorklund and Jon Cohl collect a water-quality sample at Lake Hopatcong, New Jersey, to monitor a harmful algal bloom on the lake.

This work grows from more than a decade of USGS science on HABs, and the USGS brings together scientists from many different disciplines for  HAB research efforts across the nation

View and explore water-quality conditions for the lake in near real-time:


Read the NJDEP press release on the current bloom at Lake Hopatcong:


Learn more about USGS HABs Capabilities :


#WaterQuality #LakeHopatcong #NewJersey #Science #Lake #HABs #Water #Environment 


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