Harmful Algal Blooms in Grand Rapids, Michigan

Harmful algal blooms (HABs) are an important public health concern across West Michigan, especially in and around Grand Rapids. Our region’s many lakes, rivers, and ponds—including the Grand River, Reeds Lake, Versluis Lake, and nearby inland lakes and reservoirs—can all be affected.

This guide explains what harmful algal blooms are, how they affect health, and how people in Grand Rapids can stay safe.

What Is an Algal Bloom?

Algae and cyanobacteria (often called “blue-green algae”) are simple organisms that naturally live in water. They can grow very quickly—“bloom”—when:

  • The water is warm (common in Michigan summers and early fall)
  • Water is slow-moving or stagnant (ponds, coves, backwaters of the Grand River)
  • There are high levels of nutrients, such as:
    • Fertilizer runoff from lawns and farms
    • Failing septic systems
    • Stormwater carrying pet waste or other pollutants

Blooms can occur in:

  • Freshwater (lakes, rivers, ponds, reservoirs)
  • Brackish or coastal waters (more common along the Great Lakes shoreline)

In and around Grand Rapids, harmful algal blooms are most often seen in inland lakes, ponds, and slow-moving sections of rivers, including areas that feed into Lake Michigan.

What Do Harmful Algal Blooms Look Like?

Harmful algal blooms can:

  • Look like:
    • Foam
    • Scum
    • Mats
    • Streaks or “paint-like” layers on the surface
  • Change the color of the water to:
    • Green
    • Blue-green
    • Brown
    • Red or other unusual colors
  • Collect along shorelines and in sheltered bays where the wind pushes them

Common descriptions in Michigan include:

  • “Pea soup” water
  • Bright green paint on the surface
  • Thick mats or clumps near the shoreline

Some Harmful Blooms May Not Be Visible

Not all harmful algae can be seen easily. Sometimes:

  • Toxins are present even when water looks mostly clear
  • Blooms are just beginning or breaking up and may be patchy
  • There may be no strong odor

Because of this, you cannot rely on appearance alone to know if water is safe.

When Are Harmful Algal Blooms Most Common in Grand Rapids?

In West Michigan, harmful algal blooms are most likely to occur:

  • Late spring through early fall, especially:
    • Warm, sunny stretches in June–September
  • After:
    • Heavy rain followed by hot weather
    • Fertilizer application on lawns and farm fields
    • Periods of low water flow in rivers and ponds

Cold winters and ice cover usually stop blooms, but toxins from earlier blooms may linger for a time in sediments or aquatic life.

Why Are Harmful Algal Blooms Dangerous?

An accumulation of algae or cyanobacteria that can harm humans, animals, or the environment is called a harmful algal bloom (HAB).

Some types of algae and cyanobacteria:

  • Cause skin, eye, and throat irritation on contact
  • Produce toxins (poisons) that can:
    • Affect the liver
    • Affect the nervous system
    • Cause stomach and intestinal illness (gastroenteritis)
  • Build up in:
    • Fish (especially in internal organs)
    • Shellfish
    • Crustaceans (like crayfish)

These toxins:

  • Cannot be removed by boiling, cooking, or freezing
  • Can remain in fish and shellfish for weeks to months after a bloom is gone

Important: Not all algae and cyanobacteria produce toxins, and not all blooms are harmful—but you cannot tell by sight alone. When in doubt, stay out.

Health Symptoms From Harmful Algal Exposure

Direct Skin or Eye Contact

Contact with algae-affected water can cause:

  • Skin irritation or rash
  • Itching or redness
  • Burning or stinging sensation
  • Eye irritation, redness, or watering

Wetsuits and tight-fitting clothing can trap algal material against the skin and increase irritation.

Inhaling Mist or Spray

Breathing in fine spray or droplets from contaminated water (for example, during):

  • Swimming
  • Water-skiing
  • Jet-skiing
  • Boating in choppy conditions

may cause:

  • Coughing
  • Sore throat
  • Mild breathing difficulty
  • Hay fever–like symptoms (sneezing, runny nose, irritated eyes)

Swallowing Contaminated Water or Toxins in Food

Drinking algae-affected water or eating contaminated fish or shellfish can cause:

  • Nausea and vomiting
  • Diarrhea
  • Abdominal pain or cramping
  • Fever
  • Headache

Some toxins may also:

  • Damage the liver
  • Affect the nervous system, causing:
    • Tingling or numbness
    • Weakness
    • Dizziness
    • In severe cases, difficulty breathing

If you have concerning symptoms after contact with water or seafood that may be contaminated, contact your doctor or seek urgent medical care. In Grand Rapids, emergency care is available at:

  • Spectrum Health Butterworth Hospital
  • Trinity Health Grand Rapids
  • University of Michigan Health–West (Metro Health)
  • Mercy Health facilities in the region

Who Is at Higher Risk in Grand Rapids?

Certain groups are more vulnerable to harmful algal toxins:

  • Children
    • Have more sensitive skin
    • Are more likely to swallow water while swimming
    • May not recognize warning signs
  • Older adults
  • People with weakened immune systems or chronic liver disease
  • Pregnant and breastfeeding women
  • Pets and livestock, especially dogs that:
    • Swim and then lick their fur
    • Drink from lakes, rivers, or roadside ditches

Because Grand Rapids residents enjoy many outdoor activities—like swimming, boating, fishing, and visiting lakeshore communities—awareness is especially important.

How to Tell if a Waterway May Have a Harmful Algal Bloom

Before swimming, boating, or fishing in or near Grand Rapids:

  1. Look for warning signs

    • Check for posted notices at:
      • Public beaches
      • Boat launches
      • Parks
    • Follow any instructions on signs about harmful algal blooms.

  2. Check for visual signs

    • Discolored water (green, blue-green, brown, or unusual colors)
    • Surface scums, foam, or mats
    • Thick streaks or “paint-like” layers on the water
    • Accumulations along the shoreline or in corners of lakes and ponds

  3. Consider the location and season

    • Has the area had blooms before?
    • Is it late spring through fall with warm, calm weather?
    • Is the water slow-moving or stagnant?

  4. Check local advisories

    • Kent County Health Department
    • Grand Rapids Public Health communications
    • Michigan Department of Health and Human Services (MDHHS)
    • Michigan Department of Environment, Great Lakes, and Energy (EGLE)

If you are unsure, take a precautionary approach and avoid contact.

What to Do If You Come Into Contact With Algae-Affected Water

If you think you have been exposed to a harmful algal bloom:

  1. Get out of the water immediately.
  2. Rinse off thoroughly with clean, fresh water:
    • Wash skin and hair well
    • Remove and rinse swimsuits, wetsuits, and clothing
  3. Wash and dry all clothing and equipment before using them again.
    • Pay special attention to wetsuits, life jackets, and gear that can trap algae.
  4. Avoid scratching irritated skin, which can worsen rashes or cause infection.
  5. If you feel unwell, contact:
    • Your primary care provider
    • An urgent care center (Spectrum Health, Trinity Health Grand Rapids, Metro Health, or Mercy Health clinics)
    • Call 911 for severe breathing problems, chest pain, or serious symptoms.

Keeping Children Safe Around Harmful Algae

To protect children in Grand Rapids and surrounding communities:

  • Explain in simple terms:
    • That some green or scummy water can make them sick
    • They should never drink lake or river water
  • Always supervise children near water.
  • Do not allow children to:
    • Swim in discolored or scummy water
    • Play with or touch floating mats or scum
    • Swallow water while swimming

If a child has contact with suspect water:

  • Rinse them off immediately with clean water
  • Change them into clean, dry clothes
  • Watch for any signs of rash, stomach upset, or breathing problems

Protecting Pets and Livestock in West Michigan

Pets and farm animals in Kent County and surrounding areas can be poisoned by harmful algae.

Pet Safety (Especially Dogs)

  • Do not let dogs:
    • Swim in or drink from water that is discolored or has visible scum
    • Eat algae or dead fish along the shoreline
  • Avoid walking dogs along shorelines where scum accumulates.
  • If your dog gets into algae-affected water:
    1. Rinse them thoroughly with clean water as soon as possible.
    2. Prevent them from licking their fur.
    3. Watch for:
      • Vomiting, diarrhea
      • Weakness, stumbling
      • Seizures or unusual behavior
    4. Contact a veterinarian immediately if you notice any symptoms.

Local veterinary care is widely available in Grand Rapids and surrounding communities.

Livestock Owners

For farms in Kent County and neighboring counties:

  • Check water sources frequently (ponds, ditches, troughs).
  • Do not let livestock drink from or wade in water with:
    • Discoloration
    • Surface scums or mats
  • If animals contact affected water:
    • Wash them with clean, fresh water
    • Keep them away from the source until it is safe
  • If you suspect illness:
    • Contact your veterinarian promptly

Eating Fish and Seafood During Harmful Algal Blooms

Fish, shellfish, and crustaceans can accumulate toxins from harmful algal blooms. This is relevant for:

  • Anglers fishing the Grand River, inland lakes, and Great Lakes tributaries
  • People who recreationally harvest crayfish or other aquatic species

Fish

You can often catch and release fish during a bloom. If you plan to eat fish from algae-affected waters:

  • Take these precautions:

    1. Wash the fish in clean water.
    2. Gut and gill the fish:
      • Remove internal organs (where toxins may concentrate).
    3. Fillet the fish and discard:
      • Guts
      • Liver and other organs
      • Do not feed these parts to pets or livestock.
    4. Cook fish thoroughly before eating.

  • Do NOT eat:

    • Whole fish (with organs) from algae-affected waters.

Crustaceans (e.g., crayfish)

  • Toxins can build up in their internal organs.
  • When water quality is poor or a harmful algal bloom is present:
    • Avoid eating recreationally caught crustaceans.
    • If you choose to eat them when no bloom is present:
      • Remove and discard internal organs.
      • Cook thoroughly.

Shellfish

Recreational harvesting of wild freshwater or Great Lakes shellfish is not recommended in algae-affected areas.

  • Shellfish can accumulate dangerous levels of toxins.
  • Cooking or freezing does not destroy algal toxins.
  • Eating contaminated shellfish can cause serious illness or death.

Symptoms of shellfish poisoning can appear within minutes to hours and may include:

  • Tingling or numbness
  • Weakness
  • Blurred vision
  • Difficulty breathing
  • Nausea, vomiting, diarrhea

If you suspect shellfish poisoning, seek emergency medical care immediately.

Harmful Algae and Your Drinking Water

Public Drinking Water in Grand Rapids

Most residents in Grand Rapids receive treated drinking water from a public water system. These systems:

  • Regularly monitor water quality
  • Treat water to remove contaminants, including many algal cells

If you have concerns about your tap water quality:

  • Contact your local water utility or
  • Check updates from:
    • City of Grand Rapids
    • Kent County Health Department
    • Michigan Department of Health and Human Services

Private Wells and Private Water Supplies

If you use a private well, lake intake, or cistern (more common in rural areas around Grand Rapids):

  • Do NOT use untreated algae-affected water for:
    • Drinking
    • Cooking
    • Brushing teeth
    • Showering or bathing
  • Boiling algae-affected water does not remove toxins.

To reduce the risk of algae in private water tanks:

  • Keep tanks sealed to prevent light and debris from entering.
  • Ensure pipes and fittings are shielded from sunlight.
  • Have your water tested if you suspect contamination.
  • Follow guidance from:
    • Michigan Department of Health and Human Services (MDHHS)
    • Local health departments (e.g., Kent County Health Department)

Using Algae-Affected Water for Lawns and Gardens

Avoid using algae-affected water for:

  • Lawns
  • Vegetable gardens
  • Flower beds

Risks include:

  • Potential harm to plants
  • Risk to people or animals who contact wet surfaces
  • Inhalation of toxins from fine spray (e.g., sprinklers)

If algae-affected water is the only option:

  • Use drip irrigation, soaker hoses, or a watering can to:
    • Minimize spray and mist
    • Avoid directly watering the edible parts of fruits and vegetables
  • Wash all garden produce thoroughly with clean water before eating.

Harmful Algae and Motor Neurone Disease (MND)

Current scientific evidence does not show a consistent link between exposure to harmful algae and the development of motor neurone disease (MND). Research is ongoing, but at this time:

  • Living near algae-affected water does not appear to increase the risk of MND.
  • Usual precautions to avoid direct exposure are still recommended for other health reasons.

Local Resources for Grand Rapids Residents

If you are concerned about harmful algal blooms, water quality, or health symptoms:

  • Your primary care provider (GP / family doctor)
    • For evaluation of symptoms and medical advice
  • Local hospitals and urgent care centers
    • Spectrum Health, Trinity Health Grand Rapids, Metro Health, Mercy Health
  • Veterinarian
    • If pets or livestock may have been exposed

For information, advisories, or to report a possible harmful algal bloom:

  • Kent County Health Department
  • Grand Rapids Public Health / City of Grand Rapids
  • Michigan Department of Health and Human Services (MDHHS)
  • Michigan Department of Environment, Great Lakes, and Energy (EGLE)

These agencies provide:

  • Current advisories on harmful algal blooms
  • Guidance on private drinking water safety
  • Information on recreational water quality in West Michigan

Key Points for Grand Rapids, Michigan

  • Algae and cyanobacteria can sometimes cause harm to people, pets, livestock, and the environment.
  • Harmful algal blooms are more common in warm, calm weather and in nutrient-rich, slow-moving waters common around Grand Rapids and West Michigan.
  • Seafood and fish from algae-affected water can pose health risks, especially if internal organs are eaten.
  • Not all algae and cyanobacteria produce toxins, but you cannot tell by sight alone.
  • Contact with harmful algae can cause skin, eye, breathing, and gastrointestinal symptoms, and some toxins can affect the liver or nervous system.
  • Avoid contact with water that is discolored or has visible scum, and follow all posted warnings and public health advisories.
  • If in doubt, stay out of the water, keep children and pets away, and seek advice from local health authorities.