There's danger underfoot in MidMichigan. There are coal mine shafts that have been decommissioned for decades, but there's still concern they could open up again.
The government is inspecting the old shafts to see if they must be stabilized.
The once a booming industry in Saginaw County is now covered and overgrown, hiding in the shadows of schools.
"They always pose a potential for movement, ground instability, so the office of surface mining considers these high priority projects," says Edie Zabroski of the Department of Interior's Office of Surface Mining Reclamation and Enforcement.
In December, federal government officials drilled holes at Jerome Middle School and Saginaw High School to identify exactly where the mine shafts are, how deep they run, and what kind of material was used to fill them in.
Of all the coal mines in Michigan, the Department of Environmental Quality says Saginaw County had the most and having two on school property forced the Department of Interior to investigate these first.
Inspectors at Jerome indicate the mine shaft is 145 feet deep.
Saginaw High's is 105.
They're lined and capped with timber. They're so far underground, they're underwater.
"They could be stable now but that could change overnight. They could become unstable, and you could get a ground depression or even a hole open up at anytime," says Zabroski.
Saginaw County's coal mining history dates back to its discovery in the 1850's.
At the Castle Museum, there's an exhibit paying homage to the industry that was supposed to be as successful as timber but never was.
Many families moved here after putting hope in coal.
"In the late 1890's they really started recruiting miners from outside the area," says Tom Trombley, Castle Museum deputy director.
They can trace their ancestry to Pennsylvania, Ohio, and West Virginia.
MidMichigan coal mining peaked in 1907, but the natural resource wasn't consistent and scarce.
"The last coal mine to operate in Michigan, Saginaw Co., was one in Swan Creek called the Swan Creek Mine which closed in 1952," says Trombley.
Sixty years have passed and while the feds say there's no immediate threat, they are eager to stabilize the shafts.
They're still determining when their next visit to MidMichigan will be.