About 70 guardsmen have been sent to Flint to help distribute bottled water, filters and testing kits to about 100,000 residents who cannot use their tap water.
Flint residents have complained for some time about the strange odor and color of the water coming out of their taps, but apparently nothing has been done for as long as a year. Local children show increased levels of lead in their blood, which means they are at risk of permanent brain damage.
Governor Rick Snyder is under fire for the state's slow response to the warnings.
The issue was brought up during Sunday night's debate among Democratic presidential candidates.
"If the kids in a rich suburb of Detroit had been drinking contaminated water and being bathed in it, there would have been action. So I sent my top campaign aide down there to talk to the mayor of Flint, to see what I could do to help," said Hillary Clinton.
President Barack Obama on Saturday declared a federal emergency in Flint, freeing up to $5 million in federal aid to help solve the public health crisis, but he denied the governor's request for a disaster declaration.
Civil rights activist Jesse Jackson urged Flint residents to fight for their rights during a visit Sunday.
"This is a disaster zone, not just an emergency. Maybe there should be duct tape around the city because Flint is a crime scene," Jackson said.
Filmmaker Michael Moore, a native of Flint, also blamed the governor for the water crisis and urged Obama to visit the city.
"Water infrastructure of this city has been destroyed. And it's been destroyed by the governor of this state," Moore said.
Flint's water supply system became contaminated with lead in early 2014 after the city switched its supply source from Lake Huron to the Flint River to save money, while the city waited for construction of a new pipeline to the lake. But corrosive water caused lead to leach from the old pipes.
The water supply was switched back to Lake Huron last month, but contamination remains a concern because of damaged pipes and other infrastructure.
State officials are under investigation.