The DTE Energy Foundation Trail system (https://dtetrail.org) out by Green Lake in Waterloo has a range of trails that are very popular among the mountain biking community (which was the intended primary audience for these trails), but trail runners are most welcome too (as indicated by their website and all the cyclists that wished me a great run as I ran past them today). This FKT consists of 2 connected loops: 1) the DTE Foundation Green Lake Loop + 2) the Big Kame loop as I found listed/described on the Trail Run Project. The Green Lake Loop is a very easy/fun/runnable 5 mile loop - and you access the other 5ish mile loop (Big Kame Trail) from within that Green Lake Loop. The Big Kame section is a bit more adventurous/slightly more technical but very runnable. As the signs clearly say - hikers/runners should run in the opposite direction from the mountain bikers (and there are a number of blind turns where it helps to shout out that a runner is coming around the corner just in case). Would definitely recommend this route, especially if you can go midweek and early in the day to avoid the crowds. Happy trails fellow Michigan trail friends!