Michigan environmental authorities presented a plan to federal officials on Monday to test lead-contaminated water in Flint to determine when the city's water would be safe to drink again, the agency said
The plan calls for testing in homes, schools, restaurants and the water distribution system, as well as blood testing, the Michigan Department of Environmental Quality (DEQ) said in a statement.
Some portions of the city's water system could be given an all-clear on a rolling basis before mid-April, the Detroit Free Press newspaper reported, citing other state officials.
Michigan's governor on Thursday extended a state of emergency in Flint until April 14 to help the cash-strapped city recover from the lead contamination crisis which began after it switched water sources in 2014 to try to save money.
"We want to have systems and structures in place that will lead us to better conclusions for the people of Flint," Michigan DEQ Director Keith Creagh said of the testing plan presented to the US Environmental Protection Agency.
The plan calls for four rounds of testing, each taking about two weeks, Creagh told the Detroit Free Press.
The Michigan city was under the control of a state-appointed emergency manager when it switched its source of tap water from Detroit's system to the Flint River in April 2014.
The more corrosive water from the Flint River leached more lead from the city pipes than Detroit water did.
Residents complained of various health problems from using the local water after the switch, despite officials' assurances that the water was safe.
Flint, which is about 60 miles (100 km) northwest of Detroit, returned to using that city's water in October after tests found elevated levels of lead in the water and in the blood of some children.