Officials in Lake Tahoe are telling people to avoid a popular beach after tests found high levels of bacteria in the water.
Michigan, New Mexico and Washington have also been added to the list of states with reported illnesses
The onions from McDonald's E. coli outbreak that affected dozens and killed one across 10 states have a local connection.
A California-based produce company was the source of fresh onions linked to a deadly E. coli food poisoning outbreak at McDonald's.
The lawsuit was filed one day after the CDC issued a food safety alert warning that dozens of people reported eating the Quarter Pounder sandwich at McDonald's before becoming sick.
If E. Coli levels remain this high, the swimming leg of the triathlon will have to be cancelled, according to World Triathlon competition rules, unless the organization's medical committee decides that the race can go ahead.