Minnesota’s clear, cool lakes are heating up over the summer, and those warmer waters can produce a toxic agal bloom.

“Blue-green algae is bacteria,” said Kim Laing, a surface monitoring manager with the Minnesota Pollution Control Agency. “It often looks like pea soup [or] green paint; sometimes it might have a smell to it. It thrives in warm, shallow, nutrient-rich lakes.”

Water that’s warmer than 75 degrees along with calm, sunny weather is a perfect recipe for blue-green algae, he said.

“We have had three to four degrees higher average July and August surface water temperatures in Minnesota lakes than compared to 50 years ago,” Laing said. “Our waters are warming, we have less ice during the winter.”

This means ripe conditions for blue-green algal blooms, which can be harmful to people and their pets.

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