forest in the United States and is part of the largest urban park in the United States. The Trinity River Audubon Center is a new addition to the park. Opened in 2008, it serves as a gateway to many trails and other nature viewing activities in the area. The Trinity River Audubon Center is the first LEED-certified building constructed by the City of Dallas Parks and Recreation Department. Dallas also hosts three of the twenty-one preserves of the extensive () Dallas County Preserve System. Both the Joppa Preserve, the McCommas Bluff Preserve the Cedar Ridge Preserve are all within the Dallas city limits. The Cedar Ridge Preserve was formerly known as the Dallas Nature Center, but management was turned over to Audubon Dallas group, which now manages the natural habitat park on behalf of the city of Dallas and Dallas County. The preserve sits at an elevation of above sea level, and contains a variety of outdoor activities, including of hiking trails and picnic areas. Just southwest of Dallas is Cedar Hill State Park, maintained by the Texas Parks and Wildlife state agency. A urban nature preserve, the park is located on the Joe Pool Reservoir, and offers activities such as mountain biking, birding, camping and fishing; swimming is allowed at the swimming beach only. To the west of Dallas in Arlington is Six Flags Over Texas, the original franchise in the Six Flags theme park chain. Hurricane Harbor, a large water park owned by Six Flags, is also in Arlington. References