The mayor of Toledo, Ohio, lifted the ban on drinking city tap water Monday, saying tests showed the water is once again clear of toxins.
The all-clear readings came after toxins discovered in the northwestern Ohio treatment plant had left more than 400,000 people in the region scrambling for drinking water since early Saturday. People in southeastern Michigan had also been told to avoid drinking tap water.
"We would like to thank our community for their patience and their support during this water emergency system as well as all of those who assisted during our community's moment of challenge," Mayor D. Michael Collins said in a statement.
Collins said the toxin was likely from Lake Erie algae.
The Ohio National Guard and other state agencies had been delivering pallets of bottled water to city residents and operating water purification systems to make more drinkable water.
The water problem was complicated because boiling the water, a common tool to combat contamination, only serves to make the toxin more concentrated, officials said.
Even before issuing the all-clear, Collins acknowledged that much work remains to avoid similar problems in the future.
"Once we clear this problem up, that is not going to eliminate the algae problem in the western basin of Lake Erie, that is not going to eliminate the agricultural runoff, that is not going to eliminate mega-farming," Collins said Sunday, "That is where we have to go. It's not simply looking at the (water treatment) system."
News of the contaminated water touched off a shopping frenzy at stores for bottled water and bags of ice. Stores in cities up to 50 miles away were reporting shortages of bottled water.
Toledo opened a half-dozen bring-you-own-container water distribution sites. Fire stations helped out. Families dragging coolers or lugging jugs, bottles and even cookie jars topped them off with well water funneled out of pickup trucks.
The scramble began after chemists testing water at Toledo's Collins Park Water Treatment Plant found two sample readings for microcystin in excess of the one-microgram-per-liter standard for consumption. The Federal Emergency Management Agency estimated that 500,000 people were placed under a "do not drink or boil water" advisory.
Officials said the water was not safe for drinking or cooking but healthy adults could still use it for bathing. They warned children not to bathe or swim in it because they might drink the water accidentally. Symptoms include nausea, vomiting, diarrhea and upset stomach.
Operators of water plants all along Lake Erie, which supplies drinking water for 11 million people, have been concerned over the past few years about toxins fouling their supplies. Last year, about 2,000 residents of nearby Carroll Township were prohibited from drinking water from their taps for a few days because of toxins linked to Lake Erie algae.