Michigan is home to over 11,000 inland lakes, with 300 lakes, ponds, and impoundments (i.e., a waterbody created by a dam) in the Huron River watershed alone. These waterbodies, if not managed properly, are prone to harmful algal blooms, also called HABs. Excess nutrient runoff, especially phosphorus, and other factors like rising temperatures due to climate change, have caused HABs in waterbodies throughout the state including in the Huron River watershed. For over twenty years, HRWC has monitored nutrient pollution to inform mitigation and harm-prevention strategies that combat HABs in our waterbodies.
What is a harmful algal bloom?
A harmful algal bloom (HAB) is an overgrowth of algae—often blue-green algae termed cyanobacteria—in freshwater systems like the Huron River and other waters around Michigan. HABs thrive and bloom in warm, slow-moving, nutrient-rich waters, particularly waters with large concentrations of phosphorus. When these blooms occur, they block sunlight and remove oxygen from the water as the algae decompose, threatening aquatic life. In some instances, these algae can produce chemicals that are toxic to humans and other animals.
Ford and Belleville Lakes, which are impoundments created by damming two sections of the Huron River, have had persistent HABs since the 1970s. In response, the State of Michigan created a Total Maximum Daily Load (TMDL), a nutrient control policy for phosphorus that sets a maximum threshold amount of phosphorus entering the lakes to reduce the likelihood of HABs. To support this policy, HRWC and partner local governments began monitoring phosphorus in the middle section of the Huron River watershed in 2002. This monitoring data has helped shape watershed management plans, TMDL implementation plans, phosphorus fertilizer bans, and an updated TMDL for these lakes. These regulations, broad public education, and numerous runoff reduction projects have led to measurable decreases in phosphorus inputs to Ford and Belleville lakes. Despite observed progress, HABs were still reported in these lakes in 2022 and 2023.
How wide-spread is the problem?
A combined thirteen other lakes that drain into the Huron River also had confirmed HABs in 2022 and 2023. Even though these lakes are just a small proportion of the watershed’s waterbodies, it is important to continue efforts that lower nutrient inputs to reduce and prevent future HABs. Through our Chemistry and Flow Monitoring, HRWC continues to collect nutrient data while maintaining a leadership role in the Michigan Cooperative Lakes Monitoring Program.
Both programs support data-driven approaches to restore and protect the Huron River watershed from HABs. These approaches include phosphorus bans like the new ordinance in Hamburg Township and initiatives that restore natural shorelines and manage upland landscapes like our Healthy Lakes Initiative. As a tributary to Lake Erie, these management and phosphorus reduction efforts in our watershed further support the health of the Western Lake Erie Basin ecosystem, which has also been plagued by toxic blue-green algal blooms every summer and fall since the 1970s.
HABs are a complex environmental problem that require long-term, multifaceted, collaborative efforts to reduce and prevent their occurrence. HRWC and our partners continue to promote and develop data driven policies and management strategies to support healthy lakes in our watershed and statewide, so Michiganders can continue to recreate and enjoy the beauty of our state’s many lakes for years to come.
How to report HABs
Report a suspected HAB to the Michigan Department of Environment, Great Lakes, and Energy (EGLE) at algaebloom@michigan.gov. Please include:
- Photos of the suspected HAB
- Name of the waterbody and precise location
- A brief description of the bloom location in the water
- A description of the algae you suspect is harmful (i.e., color, odor, size)
Email with a photo is preferred as scientists can often determine a HAB based on a picture, but HABs can also be reported to EGLE via phone at (800) 662-9278.
Know before you go!
Learn more about how to identify, report, and track HABs at HRWC.org/HABs.
—Kelly McCabe
This blog post is also published in the Huron River Report, Summer 2024.