The 34,000-acre St. Croix Recreational Demonstration Area takes in 21 miles of the St. Croix River, a National Scenic Riverway, which forms the park's eastern boundary, while the state-designated 'Wild and Scenic' Kettle River joins the St. Croix, forming the western boundary. At least 10 other streams flow through the park, creating a watershed of hundreds of square miles. St. Croix State Park, on the eastern edge of the Mille Lacs Uplands, has miles of trails for hikers, horseback riders, bicyclists, snowmobilers, and cross-country skiers. Swim at Lake Clayton or climb the park's firetower; on-site bike, canoe and snowshoe rentals available. Campers can reserve drive-in, walk-in, backpacking, and horseback campsites; large groups can reserve modern group centers or primitive group camps. Park lodge and All Seasons Trail Center offer toilets, showers. Naturalist programs are offered year-round; call the park office for a schedule. Located