Algae Control

The objective is to prevent algae activity, particularly blue-green algae blooms.Techniques include algaecides to kill algae, but also a number of preventive measures to reduce internal and external nutrient loading which causes excessive algae production.


HAB LAKE CLOSURES  – The stakes have been raised     April, 2019                 


For years we’ve been swimming in lakes that occasionally develop blue-green algae (cyanobacteria) blooms.  Our treatment companies have knocked down the blooms with Copper Sulfate, and the problem seemed contained.  The game has changed.  In recent years, NY State’s DEC and NJ’s DEP have been testing lakes for Harmful Algal Blooms (HABs) and asking the state Departments of Health to close the lakes if the “microcystins concentrations” exceeds a certain threshold.  It can take up to three weeks to re-open a lake depending on weather and site specific conditions.  This can be a disaster for a lake closed mid-summer.

How bad is the problem?

We’ve been swimming in lake water during algae blooms for years.  We’ve been exposed to cyanobacteria, but haven’t ingested the water, deliberately.  We might have attributed swimmer’s rashes to these conditions.  But now scientists are studying whether there is a correlation between long term cyanobacteria exposure and serious nerve diseases such as ALS.  As you would expect, lakes that have elevated microcystins concentrations are closed due to an abundance of caution.  Not to trivialize the issue, most parents of small children would keep their kids out of a lake even if there was the slightest risk of serious illness over time.

What can we do about this problem?

It behooves lake communities to take algal blooms more seriously, particularly if they are composed of cyanobacteria (also known as blue-green algae), which are the cause of more HABs in freshwater systems.  While copper sulfate can kill the algae and temporarily improve conditions, the copper lyses the cells (they burst) and cyanotoxins such as microcystins can be released into the water making them more readily available for uptake.  Thus, copper sulfate must be carefully and strategically used as part of a larger lake / HABs Management Plan.  Simply relying completely on copper sulfate does not address the cause of the problem (elevated nutrient concentrations) and can make the situation worse, such as producing larger, secondary blooms, impact non-target organisms, and actually making it easier for cyanotoxins to impact other organisms, including livestock, pets and humans.  Thus, we must redouble our efforts to avoid algal blooms “at all costs” if we expect to keep our lakes viable for swimming and other recreational purposes.

How do we avoid HABs?

We need to employ more science and testing than we’ve ever done to learn the extent to which our problem is external or internal nutrient loading, and take steps to correct the sources of the problem.  We must also do more testing to anticipate the onset of a bloom and take proactive measures.  We have to ensure that we’ve engaged the best scientific help in keeping our lakes as healthy as possible.                                                                                                                                                                                                   

Alan Fedeli, NJCOLA



Harmful Algae Blooms (HAB) - 2017


During the summer of 2017 Swartswood Lake experienced three Harmful Algae Blooms (HAB). Apparently Swartswood Lake experienced the first recorded HAB event in New Jersey, although subsequently HAB’s occurred in at least eight other New Jersey lakes during 2017. HAB’s have only recently been recognized by the industry as potentially harmful toxic events.

At the April 21, 2018 COLA meeting, guest speaker, Victor Poretti, Section Chief, NJDEP Buereau of Freshwater and Biological Monitoring, delivered an informative presentation on "Cyanobacterial Harmful Algal Blooms (HABs) - Freshwater Recreational Response Strategy and Guidance." This presentation covered several topics including the cause of algal blooms, exposure risks, monitoring and response, key contact information, treatment advisories, key contacts and websites for additional information.

Also, check out the DEP podcast on this subject:


The use of a blue or black dye to shade out UV rays thus reducing the light source for weed and algae growth.

Article: Blue Dye Shading: A Safer Way to Reduce Weeds and Algae

In an effort to reduce excessive weed growth and algae blooms, several lakes have had success with Blue Dye. The dye blocks UV light, shading the lake and reducing the photosynthesis necessary for plants and algae. Blue Dye is typically dosed in the spring, with a booster application in the summer if needed. The lake will get a “tint” of blue coloring which some will find appealing; others will call it “fake” blue coloring.  The dye is food grade, which should answer most swimmers’ concerns.  This approach is just another means by which we can minimize or avoid our dependence on copper sulfate.  Check with your lake treatment vendors for proper dosage per acre.  This approach has been successful at Cupsaw Lake, Erskine Lake, Wallkill Lake, and Lake Arrowhead.


Alan Fedeli, Chairman of Cupsaw Environmental Committee and NJCOLA board member



Past COLA Presentations

"2017 HAB Experience at Swartswood Lake"  presented by Randall Sprague at NJ COLA meeting (September 16, 2017).
The focus of this presentation was to inform the NJCOLA community on the Swartswood Lake experience, provide examples of what HAB’s might look like, identify the potential risk to humans and identify steps lake communities can prepare so that they can more rapidly respond to an HAB should it occur.The information contained in the presentation is based upon publications and web information by the World Health Organization, United States Environmental Protection Agency, New York State Department of Environmental Conservation and New Jersey Department of Environmental Protection (NJDEP). Website relied upon for the presentation are identified in the slides. Also NJDEP and Swartswood Lakes and Watershed Association met on Thursday September 14, 2017, which is factored into the presentation. It should be noted additional HAB information is contained in presentation materials by Fred Lubnow of Princeton Hydro.


“Lake Health and Property Management.”  Sabine Watson of CP Professional Services (Sept 24, 2016).

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