It is important for lake users to reasonably suspect when there is a high probability of a health risk to humans or pets when having full or partial body contact with Lake Manitou water. When in doubt, stay out.
Oakland University is conducting research on Harmful Algae Blooms (HABS) in our lake. To learn more about their research click on the website https://sites.google.com/oakland.edu/ouhabsurvey
On August 30, 2017 Lake Manitou waters developed a “whole lake” algae bloom. The lake water column contained blue-green algae. Some of it floats on the water surface as a green film. Wind and waves can move the surface layer to different areas of the lake shore where it can become highly concentrated. Avoid contact with these highly concentrated areas, including pets. Thoroughly shower after contact with any lake water.
On July 21, 2017 the east shore of Lake Manitou experienced an algae bloom that lasted two days. It presented itself as a water surface scum and extended from the Waugh channel along the east shore to the dam. It was brown and green color and had a pungent odor. The probability is that this type could be harmful to humans and pets.
On July 12, 2017 the north shore of the dam experienced a three day algae bloom. It presented itself looking like green paint had been mixed into the water. It also had a pungent odor. The probability is that this type could be harmful to humans and pets.
Avoid partial or full body contact by humans and pets in areas of the lake water where algae have accumulated into densely concentrated masses. Wind direction and wave action easily move algae suspended in the water column into concentrated masses.
Filamentous macro algae is more of an nuisance than of a health concern. It can be quite thick, but is easily removed from shorelines with the use of a rake or net. It’s great garden compost.
Article, in part, from Lake Manitou Association Newsletter June 2016: Anthropogenic Change is environmental changes created by or influenced by human activity. We see direct evidence of this seasonally in Lake Manitou water quality. Influenced by human activity, unusually high levels of dissolved phosphorus entering the lake water provide nutrients for excessive algae growth. Ongoing water testing of the Hardy-Jennings Drain is proving that during spring thaw and most rain events, large amounts of detrimental soil and phosphorus (non point pollution) enter the lake. Our lake channel that receives water from the drain is markedly less clear and always several shades greener in color than the main bodies of water. Algae flourish throughout the channel. In addition to the drain, other sources of phosphorus include septic tank leaching, lawn fertilizer runoff, pet waste and lawn clippings.
More information on algae blooms: http://www.noaa.gov/what-is-harmful-algal-bloom