We have visited this park a couple of times and have enjoyed our hikes on the Hargus Lake Perimeter Loop. The hiking trail and the mountain bike trails intersect at times, but are color marked if you pay attention to the marked trees and signs. If you miss a sign; however, you may extend your hike a bit longer than expected. The signs note that the hiking loop around the lake is 5 miles. Our fitness tracker and Apple watch clocked it a little over 4 miles instead.
It had been rainy during the week before our hike (and it rained pretty hard for a while during our hike too), so there were some muddy spots. There are a couple of tiny water crossings over logs or rocks and there are a couple of steep hill/stair spots, but they weren't too slippery or more difficult with the weather.
The park and trails are clean and well maintained with nice spaces for fishing, picnics and camping. The lake is peaceful and we are planning to return for fishing at another time.