The mayor of Toledo said on Monday that the city's tap water was once again safe to drink — lifting a three-day water ban that had affected some 500,000 people in the region.
The crisis first started Saturday, August 2, when city officials found evidence of microcystin — a toxin created by blue-green algae that can cause nausea and liver damage. The City of Toledo warned residents of the region not to drink or boil water.
The city then scrambled to conduct follow-up tests — and, at a press conference Monday, the city's mayor said that the latest tests showed the drinking water to be safe.
In particular, follow-up tests by both the Ohio Environmental Protection Agency and the US Environmental Protection Agency found that the algae-based toxin had likely dissipated to safe levels. The test results have not yet been made public, however.
There's no federally mandated "safe" levels for microcystin, but the World Health Organization recommends that levels be kept at 1 part per billion or less. Tests on Sunday night had shown levels hovering around that limit. The city said that the newest tests came back negative.
The most likely source of the toxin would be the large algae bloom that's parked itself on the western edge of Lake Erie — where Toledo gets its drinking water. These blue-green algae blooms, which are nurtured by phosphorus runoff from farms and lawns, were once a regular feature of Lake Erie in the 1960s and 1970s. They've been making a comeback in the last decade.
"It's time to stop talking about this western basin of Lake Erie and start doing something about it," said Toledo mayor Michael Collins at the press conference Monday.
The City of Toledo is offering residents advice on how to flush the water pipes in their homes. While they'll be able to start using water immediately, the city asked everyone not to start watering their lawns immediately — to avoid straining the systems.
Further reading: Here's a more in-depth look at why Lake Erie has toxic algae blooms — and what can be done to stop them.