Last week the Metroparks became aware of a Facebook post concerning a dog becoming ill after coming in contact with lake water at Stony Creek Metropark. According to the post, the dog was taken to the vet and the vet had cited cyanobacteria as a possible cause of the dogs illness. Cyanobacteria are natural and found in all Michigan lakes, but certain species can become problematic when lake conditions cause populations to expand and a harmful algal bloom (HAB) to occur. These events are rare in inland lakes, and we have been fortunate not to experience a harmful algal bloom within the Metroparks in the past.
Our staff, went out and visually examined the lake areas described in the Facebook post, and out of an abundance of caution, we reached out to our state agency contacts to provide for testing of the water for cyanotoxins, which may be produced by algae. Coordinating with staff from the Michigan Departments of Health and Human Services (MDHHS) and the Department of Environment, Great Lakes, and Energy (EGLE) samples from the lake were taken in multiple testing sites. A quick strip test for microcystin, one of the more common algal toxins, was performed at those test sites and all came back negative. A collection of algae and water was also collected and sent to a lab in Lansing for further and more complex testing. Those results showed a very low detection of anatoxin-a in one of the five testing sites. This location is an area near the dam where swimming is not permitted. The test showed a level of 4.7 parts per billion in the algae sample. The threshold for concern for human health is 80 parts per billion. There is no state determined threshold for concern for animal health.
The detected level is very low and in an isolated non-swimming area, but we do encourage park users to always practice caution with themselves, their families and their pets when swimming in lakes. There is always a chance of coming into contact with cyanobacteria or other forms of bacteria when swimming in inland bodies of natural water. Bacteria levels are in constant fluctuation within bodies of water. You should avoid swimming, or allowing your pets to swim or drink water, in areas with heavy algal growth. You should rinse yourself, children, and pets with fresh water after swimming in natural bodies of water, and familiarize yourself with the signs of a cyanobacterial bloom.