North Carolina

How to know if the algae in a pond or lake could kill your cat or dog

How can you tell if dog-killing toxic blue-green algae is in a body of water before you or your dog go for a splash or a swim?

Recent reports across the U.S. of dogs dying after coming in contact with the algae in ponds and lakes, including in Wilmington at the North Carolina coast, have raised the alarm of pet owners.

At Lake Norman, North Carolina’s largest man-made lake, officials in the Mecklenburg County town of Cornelius recently posted warning signs after the discovery of the algae in a pond at Robbins Park.

Keep away from the water’s edge for your safety,” town officials warned in an online alert after the algae appeared in the southern pond at the park, The Charlotte Observer previously reported.

“Swimming by dogs or people is prohibited,” according to the cyanobacteria (blue-green algae) alert on the town’s website, “PLEASE KEEP PETS OUT OF THE WATER!”

According to the North Carolina Department of Public Health website, no documented cases exist of people being sickened by the algae. Still, blue-green algae blooms “can produce chemicals that are toxic to animals and people who drink the untreated water,” according to the site.

Whether the algae has a bad smell or taste “is not a reliable indicator of the presence or absence of algal toxins in the water,” state health officials caution on the site.

One obvious way to know the algae bloom may be toxic is if you see large numbers of dead fish or waterfowl, according to the Utah Department of Health.

“Animals found dead may have algae around the mouth area or on the feet and legs, indicating possible ingestion of and contact with a toxic bloom,” according to the department’s website.

If you get a skin rash after being in the water, that’s another sign the algae is toxic, according to the Washington State Department of Health.

Before you or your dog take a dip, try these simple, free tests to confirm what you’re seeing is likely toxic algae, according to the Minnesota Pollution Control Agency:

With gloves on, fill a pint- or quart-size glass jar three-quarters full of the green water and leave the jar in the refrigerator overnight, with the lid screwed on, according to the Minnesota Pollution Control Agency.

If the algae settles at the bottom of the jar, “it is likely that your lake does not have a lot of bluegreen algae,” according to the agency’s website. “If the algae have formed a green ring at the top of the water, there is a strong possibility that your lake does have a blue-green algae community.”

With rubber or latex gloves on, use a long and strong stick to lift the algae from the water, without touching the algae with your hands, officials with the Minnesota agency also recommend.

“If the stick comes out looking like it has been dipped into a can of paint, the material is likely blue-green algae,” according to the agency’s website. “If the stick comes out with green strands like hair or threads, the material is probably filamentous green algae, which may be a nuisance but is not a health hazard.”

Or simply call your local health department to have the algae tested, if the algae is “bluish-green or looks like pea soup,” according to the non-profit Environmental Working Group’s website.

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Joe Marusak has been a reporter for The Charlotte Observer since 1989 covering the people, municipalities and major news events of the region, and was a news bureau editor for the paper. He currently reports on breaking news.