Environment officials have warned Minnesota's lakegoers to keep a close eye out for blue-green algae after a child fell ill while swimming last month.

Minnesota's Pollution Control Agency said Wednesday a child was hospitalized after coming into contact with toxic blue-green algal bloom in Lake Henry in Alexandria.

Earlier in June, two dogs died and several more were sickened by exposure to the algae in Red Rock Lake, also near Alexandria, but DNR chiefs have said that the blooms can affect lake waters throughout the state.

Potentially fatal to dogs, algal blooms can also affect people who come into contact with them or breathe in airborne droplets of water containing the toxins. Symptoms of poisoning include vomiting, diarrhea, rash, eye irritation, a cough, sore throat and headache.

Although not all blue-green algae is toxic, the MPCA says it might not be worth the risk swimming in a lake where it's present.

"If it looks and smells bad, don't take a chance. We usually tell people, 'if in doubt, stay out,'" Pam Anderson, MPCA Water Quality Monitoring Supervisor said in a news release. "If you're not sure, it's best for people and pets to stay out of the water."

The likelihood of blue-green algae blooms to spread rise with the temperature, and hundreds of thousands of Minnesotans will soon be heading off to the lakes for what is predicted to be a hot Fourth of July weekend.

Anyone who comes into contact with blue-green algae is advised to wash it off thoroughly as soon as possible, while pets should be rinsed off with fresh water immediately.