MINNEAPOLIS (WCCO) — The stage is set on Lake Minnetonka for a hot and sunny celebration this holiday weekend.

Big Island in particular is known for boats lining up side by side for a makeshift pool party.

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“But when we have all these people in a very small area, you know, it’s kind of like sharing a giant bath tub,” said Trisha Robinson, supervisor of the Waterborne Diseases Unit at the Minnesota Department of Health.

When you share the water so closely, you also share each other’s germs. That was the case two years ago when about 200 people got sick with a mystery illness after partying at Big Island.

“I had symptoms that are very similar to food poisoning,” said Austin Hilgenberg in July of 2019.

Those who got sick experienced cramping, vomiting and diarrhea. Some suspected E. coli was the cause. Others blamed it on people using the lake as a personal bathroom. Investigators couldn’t officially determine a cause, but they have their theories.

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(credit: CBS)

“It really looked more likely to be a viral illness, so something more like norovirus was much more likely,” Robinson said. “But again, we didn’t have laboratory testing that was conclusive to tell us that.”

State health leaders and the Lake Minnetonka Conservation District (LMCD) don’t want a repeat of 2019.

There are new rules for toilets on boats to ensure human waste isn’t getting in water. An ordinance was written making it illegal to have a macerator or grinder pump, as well as leaving a “Y” valve unlocked.

Officials are also hoping people make smart choices. That includes not drinking the lake water and making sure water doesn’t splash into the cup or can of whatever someone is drinking. And if you’re feeling sick, sit this weekend out.

“Sometimes when people are vomiting or diarrhea, they may think it’s from something they ate or drank too much of, but sometimes they’re just sick. And it doesn’t take much to contaminate an area and affect other people,” LMCD executive director Vickie Schleuning said.

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The Hennepin County Sheriff’s Office Water Patrol will also be on the lookout for people drinking and boating. There have been at least 16 BUIs on Lake Minnetonka already this year.

Jeff Wagner