The world's 2nd largest volume of fresh (liquid) water

... is contaminated with microplastic.

Now, whether or not this is a big problem is yet to be determined. 

By the way, adding up the volume of the five Great Lakes makes them the 2nd largest volume of freshwater in the world after Lake Baikal, and Baikal only surpasses them by a few hundred cubic kilometers.  Baikal has its own problems, but one of them is not being surrounded by a big population of people and several large cities.  This cannot be said of the Great Lakes.   Now, we in the USA take pride in our efforts to keep our water clean and drinkable (even though Republicans aren't exactly trying very hard to maintain that tradition, as I noted two posts earlier).  So cleaning this up might present a challenge, so the question is, does it need to be?

The first thing to figure out is if the fish are eating enough of this stuff for it be concern, and I think that's what they're going to do next.

Masses of plastic particles found in Great Lakes
 

"Now, researchers are stepping up efforts to determine how much damage the plastic could do. Mason and Rios are working with the 5 Gyres Institute, a nonprofit group based in Los Angeles that has called attention to sprawling masses of plastic in the oceans.

While Mason searches Lake Michigan for more plastic, Rios is poking through fish innards for plastic fragments. In ocean environments, fish and birds are known to feed on microplastics, apparently mistaking them for fish eggs.

A more complicated question is whether the particles are soaking up toxins in the water, potentially contaminating fish that eat them - and sending them up the food chain."

Well, even if this doesn't turn out to be a big problem, you (and I) likely won't think about the cool clear water of the Great Lakes quite the same way anymore.