Elk Rock State Park 
811 146th Avenue
Knoxville, IA 50138
641-842-6008
http://www.iowadnr.gov/Destinations/StateParksRecAreas/IowasStateParks/ParkDetails.aspx?ParkID=610155&idAdminBoundary=180
State Park: Bike, Birding, Camp, Fish, Hike, Horse, Picnic, Walk, Water Sports
An excellent system of multi-use trails radiates outward from the equestrian campground areas. There area 13 miles of equestrian trails at Elk Rock with additional mileage available on land maintained by the US Army Corps of Engineers. Mountain bikes are allowed on the trails.