In recent days, pet owners in North Carolina and Georgia reported their dogs died after swimming in water contaminated with blue-green algae toxins. (

SIOUX FALLS — As the dog days of summer drag on, pet owners are being reminded by the South Dakota Department of Game, Fish and Parks to steer clear of ponds with smelly water containing blue-green algae blooms.

Fisheries manager Mark Ermer says due to excessive spring flooding, the state has even more small ponds in unexpected places this summer.

Ermer fields a lot of questions about the dangers of blue-green algae on lakes and ponds, but says it’s fairly obvious they should be avoided.

“If you get into a blue-green algae area, and the dog drinks a significant part of that water, then yes, he can die very quickly,” he warns. “But 99 percent of people, if they had their kids or if they had a dog and they walked by a pond like this? They’re never going to let their dog go in there.”

Ermer says animals can experience symptoms within minutes of exposure to toxins in such a lake or pond.

He says symptoms might include vomiting, diarrhea, weakness, difficulty breathing and seizures.

Sensitive individuals, including young children, the elderly and people with compromised immune systems are most at risk to adverse health effects from algal toxins.

Ermer says as summer heat reduces oxygen in lakes and ponds, algae typically looks like pea soup or a thick coat of paint covering the water.

He adds that a key factor contributing to the growth of toxic algae is the amount of available nutrients from agricultural and stormwater runoff as well as leaching from septic systems.

“The fact that we use more and more chemicals on our landscapes, that’s what’s driving these systems,” Ermer explains. “That’s the fuel that creates algae blooms, is when you have high levels of those two components — especially phosphorus and nitrogen.”

Scientists studying global warming say harmful freshwater blooms are becoming more frequent and more dense and moving farther north in the U.S. than their traditional boundary

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