CHESTERTON, Ind. (AP) — Authorities plan four prescribed fires at Indiana Dunes National Park this spring, totaling more than 900 acres. Authorities say prescribed fires are used to restore the park. Exact dates have not been announced yet. The National Park Service says humidity and wind speed and direction must be ideal to complete each planned fire. The northwest Indiana park includes 15 miles of Lake Michigan shoreline and 15,000 acres of beaches, woods, prairies and marshes.