Decades ago, Lake Michigan teemed with nutrients and green algae, casting a brownish-green hue that resembled the mouth of an inland river rather than a vast, open-water lake.
Back then, the lake's swampy complexion was less than inviting to swimmers and kayakers, but it supported a robust fishing industry as several commercial companies trawled for perch, and sport fishermen cast their lines for trout. But in the past 20 years, Lake Michigan has undergone a dramatic transformation.
In analyzing satellite images between 1998 and 2012, researchers at the Michigan Tech Research Institute were surprised to find that lakes Michigan and Huron are now clearer than Lake Superior. In a study published late last year, the researchers say limiting the amount of agricultural and sewage runoff in the lake has had an immense impact. However,
the emergence of invasive mussels, which number in the trillions and have the ability to filter the entire volume of Lake Michigan in four to six days, has had an even greater effect."When you look at the scientific terms, we are approaching some oceanic values," said Michael Sayers, a research engineer at Michigan Tech and co-author of the study. "We have some ways to go, but we are getting a lot closer to Lake Tahoe. A lot of times, you'll hear from people that the water is so blue it compares to something in tropical areas."
Comment: Further reading: String of earthquakes and volcanic eruptions hits Ring of Fire - at least five events in two days