By Jessica A. Knoblauch

Summers in the Midwest are great for outdoor activities like growing your garden or cooling off in one of the area's many lakes and streams. But some waters aren't as clean as they should be.

That's in part because coal companies have long buried toxic waste known as coal ash near many of the Midwest's iconic waterways, including Lake Michigan. Though coal ash dumps can leak harmful chemicals like arsenic and cadmium into nearby waters, regulators have done little to address these toxic sites. As a result, the Midwest is now littered with coal ash dumps, with Illinois containing the most leaking sites in the country.