By Gari Voss
After two summers of a high infestation of blue-green algae that contained toxins, Cheshire Township Supervisor Steve Revor met the request of Swan Lake residents and gathered members of Michigan Environment, Great Lakes and Energy (EGLE), Allegan County Health Department, MI Department of Natural Resources (DNR), and the Allegan County Conservation District to discuss blue-green algae, its health risks, and how to determine its source, which could lead to how best to control it.
Cyanobacteria (blue-green algae) is natural in water environments. If conditions are aligned, the algae can produce toxins called cyanotoxins. Harmful Algal Blooms (HABs) can increase rapidly if a large amount of nutrients is present compared to the amount of water, and if the calm water warms. Hot, dry Julys and Augusts tend to incubate the bacteria, and large patches of blue-green algae with toxins have been detected on Swan Lake.
The Cheshire Town Hall was packed on Tuesday, April 25, 2023, and the first questions focused on the health hazards associated with blue-green algae. Environmental Health Sanitarian Nicole Taubner of the Allegan Health Department shared a PowerPoint that focused on pictures of the algae she has been testing around the lake and how it forms.
Danger to People and Pets
Regarding human health, the experts assembled were not aware of any deaths to humans. What has been observed at times is skin irritations such as rashes, hives or skin blisters if people come in contact with the algae and do not rinse their skin. It is possible that a person may have runny eyes or nose, or breathing symptoms. Nothing has been found to be long-term.
If water with blue-green algae with cyanotoxins is swallowed, it may cause short-term stomach pain, vomiting, diarrhea, weakness, numbness, headaches, dizziness or difficulty breathing. If large quantities are consumed, there may be liver or kidney damage. These symptoms may occur within hours or days.
The rule of thumb is to enjoy water activities, but stay away from areas where patches of algae are visible. It is impossible to visually determine if there are toxins in algae. If a person comes in contact, rinse off immediately after leaving the water.
The questions then moved to pets because it has been reported that dogs are affected after being in algae ridden water. MI Dept of Health and Human Services (MDHHS) info sheets shared, “Dogs are more likely to drink the scummy water and can swallow a lot of water for their size.”
It is not just swallowing the water, but dogs will lick their fur to groom themselves. If animals are not rinsed well after swimming, they may show symptoms of cyanotoxin illness. These include vomiting, diarrhea, fatigue, staggered walking, excessive drooling or convulsions. Animals have died from excessive contact.
Those in attendance learned that water recreation is fine in areas of the lake where algae is not visible. People can enjoy fishing, swimming and other water activities. If there is a large amount of blue-green algae across a body of water, avoid the water entirely.
Determining the Source
The conversation then went to what causes blue-green algae in lakes. The basic answer from the specialists is that the algae thrives where there is a high level of nutrients in warm, calm water. The nutrients to watch are phosphorus and nitrogen plus high chlorophyll levels. These are found in “lawn fertilizers, malfunctioning septic systems, animal manure, storm water runoff or sewage treatment plant discharge.”
Swan Lake is a shallower lake with minimal movement so during dry, hot summer months, the water can warm quickly. If the nutrient level is high, the blue-green algae can spread quickly and emit a bad odor.
Though Taubner has been able to identify where the toxic algae is around the lake, the testing does not tell what types of bacteria are present or the origin of that bacteria. That led Senior Environmental Quality Analyst from EGLE Janelle Hohm to share several sampling techniques that can be performed to better understand the source.
The shortest term test can be done by requesting a “blue tablet” from Taubner at the Health Department. This tablet is flushed down the toilet then the area around a septic system or holding tank can be monitored to determine if the system is leeching nutrients into the lake water. Tablets can be requested at no cost from ntaubner@allegancounty.org or by calling Nicole at 269 686-4530.
Another short term way of determining water quality is through the Lake Monitoring Training done by the Mi Clean Water Corp Cooperative Lake Monitoring Program (CLMP) that will occur in early May. Hohm encouraged people on Swan Lake to take either the in-person training on May 5 & 6, 2023 or the virtual training on May 9, 2023. This will allow volunteers to conduct quality sampling on a regular basis. When water quality problems are detected early, action can be taken to protect a lake.
A more long-term monitoring would be the sampling of the watershed system that ties to Swan Lake. Hohm suggested that Cheshire Township work with the Allegan County Conservation District to submit a Watershed Council Support Request. The testing would take a wider view of the watershed that feeds Swan Lake. Proposals for grant funding are due May 17, 2023. Caroline Keson, EGLE’s Nonpoint Source Monitoring Specialist, offered to provide assistance in developing a sampling plan. Grants can request up to $40,000, and would provide a wider view of the sources of nutrients that affect Swan Lake.
The water quality monitoring across the watershed would include the Allegan County Conservation District conducting an agricultural inventory and the health department completing the water quality monitoring.
Action to Take
The most immediate actions to take can be done by the residents around Swan Lake.
Get a blue tablet from the Allegan Health Department and test your septic system. This is entirely voluntary but extremely important. Malfunctioning systems need to be repaired or the bacteria will continue to grow.
Use laundry detergent, soap and shampoo that are phosphate-free. Many of the popular brands like All, Tide, Arm & Hammer, etc. have phosphate-free lines.
Remove animal waste from yards.
Apply fertilizer only when necessary and in the recommended amount.
Participate in water quality sampling by taking the workshop and collecting samples.
Rake areas that have weeds. Do not think that weed control will deter algae growth. It will kill the weeds that will fall to the bottom of the lake which produces more nutrients to feed the bacteria.
Skim off patches of blue-green algae then dispose of them far away from the water.
Report sightings of floating waste or algae, or unusual smells to ntaubner@allegancounty.org or call Nicole at 269 686-4530.
Longer-range actions mean controlling lake sediment over time. It begins with preventing new nutrients from entering the lake so old nutrients are reduced. Actions may include:
Watershed testing to learn the sources of the nutrients so more informed action can be taken.
Establishing a communal septic “plant”. Supervisor Revor even brainstormed an extremely long-term solution to the residents around Swan Lake which would be to build a treatment plant on Township property that bumps onto Swan Lake. That “plant” may be a series of holding tanks or a sewage treatment plant or lagoon.
Those interested in participating in the water quality training or in assisting with grant writing can contact Steve Revor at cheshiresuper@gmail.com.