TOLEDO, Ohio - The toxins that contaminated the drinking water supply of 400,000 people in northwest Ohio didn't just suddenly appear.
Water plant operators along western Lake Erie have long been worried about this very scenario as a growing number of algae blooms have turned the water into a pea soup color in recent summers, leaving behind toxins that can sicken people and kill pets.
In fact, the problems on the shallowest of the five Great Lakes brought on by farm runoff and sludge from sewage treatment plants have been building for more than a decade.
While residents around Ohio's fourth-largest city were being told to avoid drinking tap water for a second day, discussion began to center around how to stop the pollutants fouling the lake that supplies drinking water for 11 million people.
"People are finally waking up to the fact that this is not acceptable," Toledo Mayor D. Michael Collins said.
City and state officials monitoring the water were waiting for a new set of samples to be analyzed Sunday before determining whether the water was safe.
"This is not over yet," said Collins, who said some samples have showed decreased levels of toxins in the water.
Toledo officials warned residents not to use city water early Saturday after tests at one treatment plant showed readings for microcystin above the standard for consumption, most likely because of the algae.
Drinking the water could cause vomiting, cramps and rashes. Health officials advised children and those with weak immune systems to avoid showering or bathing in the water.
Worried residents told not to drink, brush their teeth or wash dishes with the water descended on truckloads of bottled water delivered from across the state as the governor declared a state of emergency. The Ohio National Guard was using water purification systems to produce drinkable water.
Oliver Arnold, of Toledo, loaded up on bottled water Sunday so that he could give baths to his six children, including 4-month-old twins. "We're going through a lot. I know by tomorrow, we're going to be looking for water again," he said.
Some hospitals canceled elective surgeries and were sending surgical equipment that needed sterilized to facilities outside the water emergency, said Bryan Biggie, disaster coordinator for ProMedica hospitals in Toledo.
In southeastern Michigan, authorities were operating water stations Sunday for the 30,000 customers affected by the toxic contamination.
The National Oceanic and Atmospheric Administration released a satellite image showing a small but concentrated algae bloom centered right where Toledo draws its water supply, said Jeff Reutter, head of the Ohio Sea Grant research lab.
The bloom was much smaller than in past years and isn't expected to peak until early September. But instead of being pushed out to the middle of the lake, winds and waves drove the algae toward the shore, he said.
"Weather conditions made it such that bloom was going right into the water intakes," said Reutter, who has been studying the lake since the 1970s, when it was severely polluted.
The amount of phosphorus going into the lake has risen every year since the mid-1990s.