Big Eau Pleine is an out of the way system that really shines September through March. The 1600 acre park itself is loaded with nature and exudes a very serene aura. Campgrounds are open May through Sept.
The trails are all on a peninsula in the Big Eau Pleine Flowage so when the water is high, the sections furthest from the main road can be quite wet and muddy. Trails closest to the Road: Popcorn, Hanna, Rock Garden, Dharma (Westside) remain relatively dry year round. All singletrack is of the older school rake & ride variety. Roots, rocks and undulating terrain are commonplace. If you like old school gnar there is some of that as well.
Park at the Winter/Horse parking lot across from the Ranger Station A-Frame about 3/4 mile in to the Park. The lot is shared with Equestrian folks but we maintain a very friendly relationship. Remember to yield to horses when riding; stop and greet. Horses are limited to the gravel doubletrack trails so be cautious when riding those trails.
Start by the Outhouse to ride the technical Rock Gardens or start down the Horsetrail to Popcorn loop. The trails are not yet marked very well but will be beginning fall 2015 and spring/summer 2016. That said, it is hard to get too lost on a peninsula. Just make your way to the blacktop road that runs through the middle of the park.
As of October 2015, there are over 9 total miles of singletrack. Several areas have just been rerouted and should have definition by Autumn. There is also a 9 mile gravel trail that runs through the park. You can mix them together for a fun 13-18 mile ride. When the flowage is low fat bikers can enjoy beach riding (sandy to rocky) the perimeter of the peninsula.
The climbs are minimal but can be challenging during Winter.