MUSEKGON, Mich. (WOOD) — It’s been a lifetime of fishing for Stanley Goodwin on Muskegon Lake.

“If it was up to me, I’d be here every darn day if it didn’t rain,” said Goodwin, who’s come for more than half a century.

But the water looked much different Monday. Muskegon Lake turned green this week as algal blooms sprouted up in the water once again.

Goodwin has seen the murky green water plenty of times, caused by algal blooms popping up in warm temperatures.

“We never knew anything when I first moved here,” Goodwin said. “Never knew anything. Called algae or algae bloom? I always thought algae was algebra.”

The city of Muskegon asked Goodwin and other residents to avoid swimming near the green blooms out of an abundance of caution until health department test results come back. The state says it’s the third time this year that algal blooms have grown like this in the lake.

“I’m always concerned about it,” said Dr. Alan Steinman, the Allen and Helen Hunting Research Professor at Grand Valley State University’s Annis Water Resources Institute.

Steinman works right off Muskegon Lake. He confirmed there have been “significant” algal blooms over the last couple of days and scientists are taking it seriously. He’s met with the Muskegon Lake Watershed Partnership about next steps and reported the problem to the Michigan Department of Environment, Great Lakes, and Energy (EGLE).

Scientists remain unsure what exactly triggers the growth of algal blooms, Steinman said. But he said they can grow under certain conditions, including sustained periods of warm temperatures and calm weather. Michigan lakes also provide sufficient nutrients for the blooms to sprout up.

That was the case over the last few days, creating the perfect storm for the algal blooms to grow. Recent windy conditions going into Wednesday stifled the bloom’s spread a bit.

Muskegon’s Department of Public Works could not confirm whether the new blooms are toxic. A representative told News 8 the city’s recommendation against swimming near the algae remains in effect until test results come back.

“We still don’t have a good understanding in the scientific community as to why some blooms are toxic and why some are not with the same exact species,” Steinman said. “In the lake, we could have the species blooming in two parts of the lake, one’s toxic and one’s not.”

Steinman said the blooms normally congregate around the bays where there’s less wind, but these went all the way toward the middle of the lake and were “widely distributed.”

The blooms turn the water green because they produce chlorophyll.

“As the algae grow, they need chlorophyll to photosynthesize,” Steinman explained. “That’s the pigment that absorbs the sunlight. When you have a lot of algae, you have a lot of pigment and it shows green.”

Steinman said even if the algal blooms are toxic, humans are more than likely fine if they come into contact. He said the only known deaths happened in South America about 30 years ago when the toxins got into the water system and people with dialysis ingested the liquid.

“You would have to intake a lot of toxins for a human to be impacted,” Steinman said.

“Obviously you wanna stay away from it,” he continued. “There’s the potential for dermatitis from the blue-green algal blooms, you would have to take in a lot of water. I’m not as concerned about that.”

The bigger concern is for pets, especially dogs. Steinman said multiple dogs die from toxic water each year around the Great Lakes.

“Dogs are more susceptible,” Steinman said. “They’re lapping up a lot of the water, it’s very problematic for them.”

That’s why Steinman says if you see green in the water, it’s best to just stay away.

“I swim in this lake, but I wouldn’t swim in an algal bloom,” Steinman said.

The scientist argued that Muskegon Lake and the Great Lakes have become much cleaner since the federal Clean Water Act went into effect in 1972. The lake’s phosphorus concentrations have declined dramatically, helping keep algal blooms down.

Steinman continues to research ways reduce the use of phosphorus on land, so water stays clean into the future.

“It’s not a Muskegon problem in my opinion, it’s happening all over the place, which goes to show we need to be working on this as a large Great Lakes community,” Steinman said. “From the research perspective, from the policy perspective to the political perspective.”