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  • chevron_rightWhat is cyanobacteria, and how does it affect our lake?
    CDC - Center for Disease Control
    Cyanobacteria Blooms FAQs
    What are cyanobacteria?
    Cyanobacteria, also called blue-green algae, are microscopic organisms found naturally in all types of water. These single-celled organisms live in fresh, brackish (combined salt and fresh water), and marine water. These organisms use sunlight to make their own food. In warm, nutrient-rich (high in phosphorus and nitrogen) environments, cyanobacteria can multiply quickly, creating blooms that spread across the water’s surface. The blooms might become visible.
    How are cyanobacteria blooms formed?
    Cyanobacteria blooms form when cyanobacteria, which are normally found in the water, start to multiply very quickly. Blooms can form in warm, slow-moving waters that are rich in nutrients from sources such as fertilizer runoff or septic tank overflows. Cyanobacteria blooms need nutrients to survive. The blooms can form at any time, but most often form in late summer or early fall.
    What does a cyanobacteria bloom look like?
    You might or might not be able to see cyanobacteria blooms. They sometimes stay below the water’s surface, they sometimes float to the surface. Some cyanobacteria blooms can look like foam, scum, or mats, particularly when the wind blows them toward a shoreline. The blooms can be blue, bright green, brown, or red. Blooms sometimes look like paint floating on the water’s surface. As cyanobacteria in a bloom die, the water may smell bad, similar to rotting plants.
    Why are some cyanbacteria blooms harmful?
    Cyanobacteria blooms that harm people, animals, or the environment are called cyanobacteria harmful algal blooms. Harmful cyanobacteria blooms may affect people, animals, or the environment by:
    • blocking the sunlight that other organisms need to live. Cyanobacteria blooms can steal the oxygen and nutrients other organisms need to live.
    • making toxins, called cyanotoxins. Cyanotoxins are among the most powerful natural poisons known. They can make people, their pets, and other animals sick. Unfortunately, there are no remedies to counteract the effects.
    You cannot tell if a bloom has toxins by looking at it.
    How can people and animals come in contact with cyanobacteria and cyanotoxins in the environment?
    People and animals can come in contact with cyanobacteria and cyanotoxins that are in the environment by:
    Drinking water that comes from a lake or reservoir that has a cyanobacteria bloom.
    Swimming or doing other recreational activities in or on waters that have cyanobacteria blooms.
    How do I protect myself, my family, and my pets from cyanobacteria blooms?
    To protect yourself, your family and your pets from cyanobacteria blooms:
    • Don’t swim, water ski, or boat in areas where the water is discolored or where you see foam, scum, or mats of algae on the water’s surface.
    • Do not allow children or pets to play in or drink scummy water.
    • If you do swim in water that might contain harmful cyanobacteria, rinse off with fresh water as soon as possible afterward.
    • Don’t let pets or livestock swim in or drink from areas where the water is discolored or where you see foam, scum, or mats of cyanobacteria on the water’s surface.
    • If pets, especially dogs, swim in scummy water, rinse them off immediately. Do not let them lick the cyanobacteria off their fur.
    • Report any “musty” smell or taste in your drinking water to your local water utility.
    • Follow any water-body closures announced by local public health authorities.
    Why do dogs get sick more often than people from cyanobacteria blooms?
    Dogs will get in a body of water even if it looks or smells bad, including when it contains cyanobacteria. Dogs are also more likely to drink the contaminated water.
    How are people or animals that have been exposed to cyanobacteria toxins treated?
    • If you or your pet comes in contact with a cyanobacteria, wash yourself and your pet thoroughly with fresh water.
    • If you or your pet swallow water from where there is a harmful algae bloom, call your doctor, a Poison Center, or a veterinarian.
    • Call a veterinarian if your animal shows any of the following symptoms of cyanobacteria poisoning: loss of appetite, loss of energy, vomiting, stumbling and falling, foaming at the mouth, diarrhea, convulsions, excessive drooling, tremors and seizures, or any other unexplained sickness after being in contact with water.
    How can you help reduce cyanobacteria blooms from forming?
    • Use only the recommended amounts of fertilizers on your yard and gardens to reduce the amount that runs off into the environment.
    • Properly maintain your household septic system.
    • Maintain a buffer of natural vegetation around ponds and lakes to filter incoming water.
    Is there testing for cyanobacteria toxins?
    Yes, but the testing is specialized and can only be done by a few laboratories. Scientists are working to develop toxin test kits for water resource managers and others.
  • chevron_rightWhat is the basic concept of phosphate binding?
    Phoslock is a patented phosphorus locking technology to restore water quality in ponds, lakes and reservoirs. Phoslock was developed by the Australian national science agency, Commonwealth Scientific and Industrial Research Organization (CSIRO), to remove phosphorus from water bodies and restore water quality. For over ten years, Phoslock has been successfully used in water resource restoration programs around the world. Although Phoslock is a new technology to the United States (2010), it is rapidly emerging as the most effective phosphorus inactivation and water quality restoration solution for ponds, lakes and reservoirs.
    Phoslock works by utilizing the ability of lanthanum to react with phosphate. Removal of phosphate by lanthanum is highly efficient and has a molar ratio of 1:1 which means that one ion of lanthanum will bind with one ion of phosphate. This binding forms the mineral Rhabdophane (an insoluble and biologically inert compound) which strips phosphate from the water.
  • chevron_rightWhy is phosphate binding recomended for Lake Harwntom?
    Problem:  We have a history of cyanobacteria (blue-green algae) blooms, which have resulted in late season beach closures and the presence of cyanotoxins in the water column. In high amounts, cyanotoxins are harmful to pets and humans. A significant driver for these blooms is phosphate released from sediment when oxygen is low in deep waters during the summer.  This process is called internal loading.
    Potential Solution:  "Bind" the phosphate in the sediment of deep water, to reduce internal loading in the summer, thereby reducing the phosphorus algae need to grow.  The binding will be accomplished by distributing a lanthanum-modified bentonite clay (Phoslock) in the deep end of the lake.
    Background: Internal Nutrient Loading, Impact, and Control Options:  Our lake is impacted by watershed nutrient sources like storm water runoff and septic systems.  Nutrients from the watershed partially settle out to the lake bottom every season, and contribute to long-term nutrient enrichment, or eutrophication, over time. Nutrients from bottom sediments are recycled into the water column during summer periods of low oxygen (anoxic) deep waters. Sediment release of phosphate is referred to as “internal loading,” and can disproportionately influence cyanobacteria (blue green algae) blooms, compared to watershed inputs. Cyanobacteria have the ability to adjust their height in the water column by regulating their buoyancy. This adaptation allows cyanobacteria to take advantage of nutrients in deeper water, before rising to the surface to reach more sunlight.
    While long-term lake management requires improvements to watershed nutrient loading, it is possible to reduce summer nutrients and subsequent cyanobacteria blooms through in-lake treatments that are designed to bind phosphate. The two main types of phosphate binders used in lakes are aluminum sulfate (Alum) and a lanthanum-modified bentonite clay (Phoslock). These products can be applied to a lake to target phosphate in the water column or to target phosphate in sediment, to reduce annual internal phosphate loading, thereby restricting growth of blue green algae. 
    Recent developments:  In 2020 we experienced an algae bloom with extremely low rainfall, indicating internal loading could be a major contributor to blooms.  In 2021, we sampled deep sediment  to determine the form and concentration of phosphorus in deep sediments. Based on the sample analysis and other factors, our limnologist recommended a Phoslock application to reduce internal loading. Alum is not recommended, due to potential environmental impact.
  • chevron_rightHow can I learn more about the phosphate binding proposal?
    Refer to FAQ's from the manufacturer here:  Phoslock  
    Technical information may be found here:  Technical Bulletin
Geese and Waterfowl
Water Quality
  • chevron_rightDo we test for high bacteria levels at our beaches?
    Yes, we do.  A volunteer periodically (every two weeks or so) collects two samples from each of our three beaches, and hand delivers them to Torrington Area Health District (TAHD). They consolidate our samples with samples from other lakes for lab testing to determining if bacteria levels are acceptable for bathing.  There are numerous forms of bacteria, so the test is for E. Coli only, which serves as an indicator organism.   If the sample indicates bacteria levels are unsatisfactory for bathing, a re-sample is taken, and if it still is in the unsatisfactory zone, our protocol is to post a notice to take precautionary measures when swimming at the beach until a test indicates a satisfactory result. 
    Here is a sample report:    TAHD Bathing Water Sampling Report   
    Factors that have an influence on water quality include bather loading, rainfall, storm water discharges, sanitary conditions on the watershed, and large populations of waterfowl in the watershed.  In the case of Lake Harwinton, goose droppings on the beaches are typically the cause of high bacteria levels. 
  • chevron_rightWhat is that stuff that looks like pea soup or spilled paint on the water's surface?
    It may be blue-green algae, which can be potentially harmful.  Go to Blue Green-Algae for more information.
  • chevron_rightWhat is the foam I see at beaches and the lake shore?
    Most foam observed in lakes and streams is a product od nature; foam is not necessarily an indicator of pollution.  All lakes contain organic matter, such as algae and plants, and when these decompose they release cellular products (surfactants) into the water, which lessens the surface tension. When the wind blows, the waves on the lake agitate this surface agent, thus transforming it into sudsy foam. For facts on the causes and sources of foam, refer to the NH Fact Sheet on lake foam.
  • chevron_rightWhy does the lake water often have a yellow-brown hue?
    Lakes that are surrounded by coniferous forests (evergreens such as pine, spruce, hemlock and fir trees) are generally brown in color because pine needles that fall to the ground are very slow to degrade. This is also true of lakes surrounded by wetlands, where plants decompose very slowly. Naturally occurring organic compounds such as tannins and lignins, derived from the decomposition of plant and animal matter, can give surface water and groundwater a tea-like yellow-brown hue, as well as a musty smell, is known for its "root beer" color. The brown coloring comes from tannins leaching into runoff water from tree roots and decaying vegetation.
Weeds and Algae




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