What is an algae bloom?
Algae are microscopic organisms that grow naturally in oceans and fresh waters. In Michigan, they are more likely to appear on lakes, ponds and streams in late summer or early fall. Under certain conditions, some algae can grow into a large visible mass called a ‘bloom’.

Are algae blooms a health concern?
Not all blooms are harmful, but some species of algae, such as cyanobacteria or blue-green algae, can produce toxins or poisons that can cause serious illness or death in pets, livestock, wildlife and humans.

How will I know if a toxic algae bloom is present?
Algae blooms appear as thick foam or scum on the water’s surface. They can be bright green, blue- green, white or brown in color. The water may look like paint. Unfortunately, you cannot tell if an algae bloom is toxic just by looking at it. If you come across areas of thick algae, take precaution by avoiding water contact and keeping pets out of the water.

What are the health risks posed by exposure to toxic algae?
Skin irritation or rash is the most commonly reported health effect. Other symptoms range from diarrhea, cramps and vomiting to fainting, numbness, dizziness, tingling and paralysis. The most severe reactions occur when large amounts of water are swallowed. The chronic effects of long-term exposure to algae toxins are being studied.

Can blue-green algae make my pet sick?
Animals are not necessarily more sensitive to blue-green algal toxins than humans. However, many animals, such as dogs and cattle, enjoy being in the water, even if there is an unsightly green scum layer floating on top. When such a bloom is present, animals may consume large quantities of blue-green algae if they drink the water. These animals can become very ill, and even die. Symptoms of blue-green algal toxin poisoning may range from lethargy and loss of appetite to seizures, vomiting, and convulsions. Dogs are particularly susceptible to blue-green algal poisoning because scums can attach to their coats and be swallowed during self-cleaning. If your dog does enter scummy water, rinse them off immediately.

How can I protect my family and myself?
Do not swim, water ski, or boat in areas where the water is discolored or where you see foam, scum, or mats of algae on the water. Keep children and pets away. Never drink or cook with the affected water. If you touch the affected water, wash off thoroughly with fresh water. Most importantly, respect any water-body closures announced by local public health authorities. If you irrigate your lawn, don’t irrigate with water that looks scummy or smells bad.
 
Can I treat algae-affected water to make it safe?
No. Personal water filtration devices that may be purchased in outdoor recreational stores have not been proven to be effective. Boiling water will not remove the toxins.

How do water treatment plants deal with blue-green algae?
Conventional water treatment facilities remove the cells of algae and other growing organisms by adding chemicals that bind them together during their processing. As the cells clump together, they become heavier and fall to the bottom of settling basins. Additional removal is obtained by filtration and through the use of activated charcoal.

Is it safe to eat fish?
Fish caught in affected waters pose unknown health risks. If you choose to eat them, remove all fat, skin and organs before cooking because toxins are more likely to collect in these tissues. Do not eat fish or crayfish harvested from affected waters.

My drinking water comes from a water source that is affected by algae blooms. Am I at risk?
People who draw water directly from an affected water body are advised that it may be dangerous to drink. If you or your drinking water supplier uses water from an affected source, call and ask if the water has been tested. If it has not been tested, it is recommended that you use an alternative water source not affected by the bloom.

How can I help reduce the occurrence of blooms?
If you use fertilizers and pesticides on your yard, use only the recommended amount to reduce nutrient loading. Homeowners with an on-site sewage disposal system can also minimize nutrient loading by properly maintaining their system. If your property is on a pond or lake, maintain a buffer of natural native vegetation at the water’s edge to filter incoming water.