Pleasant Hill Dam Site has good trails.
Pleasant Hill Lake is approximately 20 miles east of I-71. At I-71 take Exit 165, take State Route 97 east, travel 4.6 miles past the village of Butler, Ohio and turn left onto McCurdy Road, go two miles and turn right on Goon Road. It's 1.2 miles to the dam.
http://www.tripleblaze.com/trail.php?c=3&i=7424