Why you should check this map before letting your dog swim in Michigan waters

Harmful algal blooms increase in Michigan

Landsat satellites captured this image of Lake Erie during a harmful algal bloom event in 2017. (USGS)

There’s an increasing problem plaguing some bodies of water in Michigan, and it could be deadly for your pets.

Harmful algal blooms, known as HABs, peak in the summer and can often be found in lakes, river and streams across the state. The issue was so bad on Lake Erie that back in 2014 it disrupted drinking water quality for thousands of residents.

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In Michigan, algal blooms typically occur during periods of warm temperatures, lots of sun, and high nutrient levels. The number of such reports, particularly the occurrence of cyanobacteria or blue-green algae blooms and concern over the possible presence of algal toxins such as microcystin, appear to have increased in recent years, according to the state.

Michigan’s health department says it’s not possible to determine whether algal blooms contain harmful toxins by looking at them, so it is best to avoid contact with any body of water that is covered with algal mats or significant rafts of algae on the surface.

---> Check the map: Michigan also has an interactive map that shows where HABs have recently been detected. As of July 11, 2024, the closest confirmation near Detroit was Portage Lake in Livingston County. There were a handful of others on the west side of the Mitten and Up North.

Here’s some FAQ on HABs from Michigan EGLE:

What does a harmful algal bloom look like?

Not all algal blooms have cyanotoxins, so it is difficult to tell if it is harmful by looking at it. Harmful Algal Blooms (HABs) can be a variety of colors such as green, blue-green, blue, brown, yellow, white, purple, or red. HABs can look like scums in the water and may have small flecks, foams, or sometimes globs and mats floating in it. The water can also look like it has spilled paint or a green sheen on the surface.

More information, pictures, and a video description of HABs can be found here.

Can I swim, fish, or go boating if I suspect a harmful algal bloom may be present?

It is best to not swim, wade, or touch the water where harmful algae may be present. Algae can thickly cover the surface of the water making it difficult to see underneath to tell how deep the water might be or see rocks in the water. Trying to wade or swim through thick algae could be dangerous.

Unless a Harmful Algal Bloom (HAB) covers a large part of the lake, people can lower their risk of contact with harmful algae by using an unaffected part of the lake.

People and pets should be rinsed thoroughly in fresh water if there has been any skin contact with a HAB. People and pets should avoid the water entirely, including fishing and boating activities, if there is a large HAB spread out across the waterbody.

What are the health effects of harmful algal blooms in people?

Skin contact with Harmful Algal Blooms (HABs) may cause irritation such as rashes, hives, or skin blisters. It may also cause runny eyes and nose or asthma-like symptoms. Thoroughly rinse off with fresh water if the skin comes into contact with a HAB.

Recreational water sports like boating and jet skiing may create water spray into the air. If HABs are present, contact with the airborne cyanotoxins in the spray may cause skin, eye, nose, or throat irritation.

Swallowing large amounts of water having cyanotoxins in it may cause stomach pain, vomiting, diarrhea, weakness, numbness, headaches, dizziness, or difficulty breathing. Frequently swallowing or swallowing large amounts of cyanotoxins can harm the liver or kidneys.

Symptoms of illness from cyanotoxins may appear within hours to days. If symptoms do appear, the severity will depend on the type of cyanotoxins with which the person had contact, how the person had contact (touching, swallowing), and how long the contact lasted.

If you may have had contact with or swallowed water containing cyanotoxins, and have any of the symptoms listed above, talk to your doctor or call Poison Control at 800-222-1222. If symptoms are severe, get emergency medical attention as soon as possible.

What are the health effects of harmful algal blooms on pets or livestock?

If you see a possible Harmful Algal Bloom (HAB), do not allow your pets or livestock to come into contact with it-especially dogs.

Dogs are more likely than people to drink scummy water and can swallow a lot of water for their size. Because dogs can swallow cyanotoxins when they groom or lick themselves, it’s important to rinse them off with fresh water after contact with water that may have had a HAB.

Symptoms of illness from cyanotoxins often appear quicker in animals than in people-sometimes in minutes to a few hours. Symptoms in animals can include: vomiting, diarrhea, fatigue, staggered walking, excessive drooling, and convulsions. Deaths can occur.

Contact a veterinarian immediately if pets or livestock have had contact with a HAB or are showing signs of illness. If you think your pet or livestock is ill due to a HAB, report it to the Michigan Department of Agriculture and Rural Development, Animal Industry Division (AID), at 800-292-3939. The AID is attempting to track HABs to help protect pets and livestock.

What causes a harmful algal bloom?

A Harmful Algal Bloom (HAB) can happen when the water temperature is warm, the lake is calm, and there is a high level of nutrients, like phosphorus or nitrogen, in it. High levels of nutrients can come from pollution such as lawn and farm fertilizers, malfunctioning septic systems, animal manure, storm water runoff, and sewage treatment plant discharges. Invasive zebra and quagga mussels help make water conditions right for HABs. They eat other algae but release cyanobacteria back into the water.

Can I eat fish if harmful algal blooms are in the water?

When Harmful Algal Blooms (HABs) are present, the meat of fish (the filet), and especially the guts and organs (liver, kidney, etc.) may have small amounts of cyanotoxins. The amount of cyanotoxins found in fish depends on several factors, including how badly and for how long the cyanobacteria has been blooming in the area where the fish are caught.

Following the Eat Safe Fish waterbody-specific guidelines, or Statewide Safe Fish Guidelines, and eating only the filets (and not the guts) lowers the potential health risk of eating fish from areas affected by HABs and from other chemicals that might be found in them. The guts should be thrown away and filets should be rinsed with fresh water before cooking.


About the Author

Ken Haddad has proudly been with WDIV/ClickOnDetroit since 2013. He also authors the Morning Report Newsletter and various other newsletters, and helps lead the WDIV Insider team. He's a big sports fan and is constantly sipping Lions Kool-Aid.

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