Blue-Green Algae Primer for Ballston Lake by Tim Sorrentino

What is it?

• What we observe as blue-green algae is actually toxic bacteria called cyanobacteria. Sunlight, warm and still water, and nutrients contribute to cell growth and blooms. Photos gallery on how to identify them.

• Cyanobacteria may contain one or more toxins within the cell and cell walls called cyanotoxins.

• Cyanobacteria toxicity levels are difficult to measure and can vary from cell to cell and bloom to bloom. One way to roughly gauge probability of toxicity is by appearance; the higher the concentration, based on thickness of the floating cells on the water and viscosity, is likely to be indicative of higher levels of toxicity. HOWEVER, there are many different toxins that may be present in a single cell or a single bloom, which even in small colonies, could contain high or even lethal levels of toxins.

Algal blooms may have the appearance of spilled green paint

• The EPA and DOH explained that Ballston Lake is likely to have microcystins present in the cyanobacteria. A. Anatoxin, Cylindosporum and Saxotoxin are less likely to be present, but may eventually migrate to NYS waters as with any unwanted marine lifeform.

• Cyanobacteria blooms can be harmless. The best way to determine the presence or absence of cyanotoxins is laboratory testing, which may be costly and take time to receive results.  For example: some BLIA volunteers take water samples if they are aware that blue-green algae has been sited. They perform a quick test to confirm presence or absence of toxins and send a notification email to the 300+ BLIA members and others. Also, samples are sent to a lab in Syracuse to confirm results within a few days. The blooms are typically gone within 48 hours, possibly prior to lab testing confirmation.

• Cyanobacteria and cyanotoxin life cycles vary based on several factors and are not predictable. The best way to determine the presence or absence of cyanotoxins is laboratory testing.

How can it affect humans, pets, and fish?

• Cyanotoxins enter lifeforms (humans, pets, fish, and plants) through ingestion of affected water, airborne ingestion by breathing in water droplets (mist or spray) or absorption through skin, mucosal or other tissue. Pets, particularly dogs that enter infected waters, will get a coating of cyanobacteria on them, and ingest the bacteria by subsequently licking their coat.

• Toxins present in cyanobacterial cells can affect liver, digestive and neurological functions as well as cause irritation to skin and tissue. Symptoms are wide ranging and may be unnoticeable, temporary, permanent, or even fatal for both humans and pets. The effects of cyanotoxins are not predictable.

• Fish can accumulate cyanotoxins in their livers as well as muscle tissue. Consumption of fish from an affected body of water may be detrimental to your health.

• Very little information is known about edible plants that are exposed to cyanotoxins. It is likely that the toxins can accumulate in the flesh of the fruits and vegetables and may therefore be inadvisable to consume produce that may have come in contact with cyanobacteria tainted water.

• There are no known treatments once the toxins have entered a lifeform.

How can contamination be minimized?

• Awareness is key! New York State Department of Environmental Conservation reports Harmful Algal Blooms (HABs or cyanobacteria) sightings on many NYS bodies of water including Ballston Lake. Their website is updated on a weekly basis with information for each monitored body of water. You can subscribe to receive notices and emails on the DEC website. The HAB reports can be found at: .

• DEC mostly relies on the public to report sightings. If you suspect that blue-green algae is present, you can use this link, provided by NYS DEC, to submit a report:

• If HABs warnings are posted or you notice a bloom, avoid direct (wading, swimming, watersports, ingestion) and indirect (mist or spray commonly encountered while boating) contact with water.

• Reduce or eliminate the sources of nutrients. Cyanobacteria are fed by the same nutrients that cause so many of the unwelcome aquatic plants to flourish in the lake. The sources of these unwanted nutrients include fertilizer run off from farms in the watershed, “leaky” septic systems that allow nutrient rich effluent to enter the water and specific to Ballston Lake, and the large amount of phosphorus at the bottom of the lake. The completion of the Ballston Lake sewer system (which means attachment of all houses in the watershed) is currently 2028. This will eliminate one of the three major “food” sources for cyanobacteria.

• Prevent pets from entering and drinking lake water.

Can lake water, intended for domestic use, from a private residential water intake be treated to eliminate cyanobacteria and cyanotoxins?

• Some municipal water districts use fresh bodies of surface water for residential use. They use different treatment techniques and continuously test from point of intake to the point of use to verify water purity.

• There are no “approved” private residential point-of-use water treatment systems that can be installed in your home for removal of cyanobacteria and cyanotoxins. Companies that sell and maintain residential water treatment systems and components are by and large unfamiliar with cyanobacteria and cyanotoxins.

• The National Sanitation Foundation (NSF) has point-of-use water filters approved for “reduction” (NOT elimination) of microcystins. These are just one of the toxins that may be present in cyanobacteria.

• Boiling water to “purify” will likely cause cyanobacterial cells to rupture and release the toxins into the water. Chlorination and other oxidation methods are also likely to result in the rupture of cells and release of toxins. These measures have the opposite desired effect!

• Whole house reverse osmosis or ozone systems may eliminate all toxins. They are much more expensive than other water treatment systems and require continual water testing and maintenance to ensure efficacy.

• If your only option is to draw water from the lake for domestic use, consider the following treatment system configuration that might reduce cyanobacteria and cyanotoxins in your drinking, cooking, and bathing water:

    • Stage 1 - large 20-micron polyester pleated filter (at least 8” diameter and greater than 24” in length) at the point of intake. This should stop the intake of zebra mussel larvae and other larger sediments from entering the system. The intake should be placed as far from shore and as deep as possible. Cyanobacteria tends to gather and sink at the shoreline.
    • Stage 2 - 5-micron filter for particulate and sediment removal. This filter should be sized appropriately for water flow and consumption needs and located in the house.
    • Stage 3 - 1-micron (actual) filter for fine particulate and sediment removal. This filter may remove cyanobacteria cells. This filter should be sized appropriately for water flow and consumption needs and located in the house.
    • Stage 4 (optional) - whole-house granular activated carbon tank in combination with a chlorine contact tank system. (EPA recommends carbon treatment prior to chlorination. Traditional treatment systems place chlorination prior to carbon).
    • Stage 5 - multistage point-of-use reverse osmosis system that includes powder activated carbon for cooking and drinking water.
    • Note: personal protective measures (skin, eye, mouth) are advised when changing filtration media or working with filtration equipment.

• Using the above type of filtration and disinfection system may reduce the amount of or eliminate toxins, particularly microcystins. However, other toxins such as A. Anatoxin, Cylindosporum and Saxotoxin may still be present in the water and would probably require daily laboratory testing to determine whether toxins are present. Laboratory testing is usually impractical in a residential system not only because it’s costly, but it takes days to process each sample, in which time contamination of humans and pets can occur.

• The use of bottled water for drinking and cooking may reduce the likelihood of contamination by ingestion for humans and pets. This does not preclude contamination caused by contact with skin or mucosal membranes.

• Other cautionary notes:

    • Washing dishes by hand or in a dishwasher does not necessarily eliminate the toxins from kitchenware (pans, dishes, glasses, flatware, etc.)
    • Toxins may be absorbed through skin or mucosal membranes while bathing or showering. Incidental ingestion may occur while showering.
    • Cyanobacterial blooms can occur in the winter, depending on conditions, to a lesser degree with a lower probability.


In summary, Ballston Lake has cyanobacteria present and has tested positive for microcystins. Not every bloom contains microcystins, local testing by BLIA volunteers may detect presence. If so, notification emails are sent to the 300+ BLIA members and others. Subsequently, samples are sent to a lab for final disposition of presence or absence. Perhaps safer to assume that blooms contain microcystins. Subject matter experts believe that Ballston Lake may be at risk for increasing levels of toxins. Local and national residential point-of-use water treatment companies do not appear to be knowledgeable nor equipped to safely mitigate or eliminate toxins from water drawn from the lake for domestic use. Commercial or municipal water treatment facilities have the equipment, materials, scientists, and technicians to continually monitor and treat water to eliminate toxins. There is currently no prescriptive formula to scale these monitoring and treatment methodologies to private point-of-use residential systems.