SUTTONS BAY -- A study of E. coli levels in Grand Traverse Bay shows it's not overwhelmed with algae growth and accompanying bacteria.
Area residents should try to keep it that way, experts said.
Last year, scientists from Grand Valley State University sampled six beaches in Grand Traverse Bay and two in Little Traverse Bay. They collected water samples and some cladophora algae samples to test E. coli levels.
"Grand Traverse Bay is certainly in really good shape. There are some amounts of algae that wash up on shore. There's always some E. coli and we did find some E. coli in the algae," said Richard Rediske, water resources professor.
Researchers found far greater amounts of cladophora algae in Saginaw Bay, along with correlating higher levels of E. coli, he said.
"You need to continue to be good stewards of your water. You have a good resource there. Just a little more phosphorous would stimulate cladophora growth and you'd have more of it washing up on your beaches," Rediske said.
Rediske will discuss the E. coli study results at a free seminar at 7 p.m. March 5 at the Inland Seas Education Center in Suttons Bay.
Researchers sampled for eight weeks and only once found algae at Clinch Park, although West End Beach had algae about half the time during the study, he said.
"In general, the beach with the most algae accumulation was Bryant Park. Parks near stormwater discharges had higher levels of E. coli," Rediske said.
Traverse City State Park beach also had some algae growth and higher levels of E. coli were found near Mitchell Creek's outlet, he said.
Excessive cladophora growth in nearshore areas may have public health and ecological importance. Experts suspect that invasive zebra and quagga mussels on the lake bottoms filter the normally murky Great Lakes waters to a degree that more sunlight enters the water, causing increased algae growth.
E. coli in algae is not necessarily a health hazard, said Tom Buss, environmental health director for the Grand Traverse County Health Department, but its presence can indicate other bacteria in the water that could cause illness.
"If it's present, I wouldn't be swimming in areas with a lot of algae and would stick to the sandier areas," Buss said.
The health department sometimes temporarily closes area beaches when E. coli levels rise; last season Traverse City State Park and Bryant Park briefly closed because of high E. coli readings, he said.
A future E. coli source-tracking study along the Boardman River and other drainage points into the bay would be beneficial, Buss said.
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