Toledo Mayor D. Michael Collins raises a glass of tap water before drinking it during a news conference in Toledo, Ohio, Monday, Aug. 4, 2014. A water ban that had hundreds of thousands of people in Ohio and Michigan scrambling for drinking water has been lifted, Collins announced Monday. (AP Photo/Paul Sancya)

The worry over another water emergency along Lake Erie is far from over.

That's because the algae that left behind toxins contaminating the of 400,000 people in Ohio isn't supposed to peak until September.

Water plant operators and residents who get their water from the western end of Lake Erie will be holding their breath over the next few months.

The chances of more trouble will depend a lot the winds, rains and temperatures that determine how large the algae grow and where it ends up.

It's still not clear what role the algae-induced played in fouling the water supply for the city of Toledo beginning Saturday.

Toledo Mayor D. Michael Collins listens to a question during a news conference in Toledo, Ohio, Monday, Aug. 4, 2014. A water ban that had hundreds of thousands of people in Ohio and Michigan scrambling for drinking water has been lifted, Collins announced Monday. (AP Photo/Paul Sancya)

Investigators also are looking at the city's aging water supply system and how it operates.