CHICAGO - More than half a million people are under a state of emergency in Toledo, Ohio as water supply from Lake Erie is unsafe to drink.

Algae is seen near the City of Toledo water intake crib, Sunday, Aug 3, 2014, in Lake Erie, about 2.5 miles off the shore of Curtice, Ohio. [Photo/IC]

A deadly chemical called microcystin was found in excess of the recommended amount coming from the City of Toledo Water Plant and Governor John Kasich has issued a declaration in three counties Saturday.

Residents of Toledo are being told not to use the water for drinking, making infant formula, making ice, brushing teeth, or preparing food. They have waited for word on when their water will be safe to drink for more than 24 hours.

Tests of water have been sent to the US Environmental Protection Agency and are pending analysis.

In a news conference, Toledo's mayor D. Michael Collins said Sunday that tests of the water supply were going to take longer than expected.

Toledo's drinking water comes from Lake Erie, where a harmful algae bloom that causes microcystis has been growing, according to a city official.

Chicago officials said Sunday the government is re-testing its Lake Michigan water supply as a safety precaution.

Chicago Department of Water Management spokesperson Gary Litherland said the test results would likely be available in a day or two.