There are science fairs and there are marathons. Today, it’s the fifth annual Iowa Envirothon. The event is gathering dozens of Iowa high schoolers in Guthrie County to test their knowledge in areas ranging from aquatics to forestry and from soil conservation to wildlife.Aaron Putze is spokesman for the Iowa Farm Bureau, which is co-sponsoring the contest. It draws 16 teams of students from high schools across Iowa to Springbrook State Park near Guthrie Center. They’ll have to trek through the park to various stations and answer questions about environmental issues and give oral presentations on wetlands.The winning team will represent Iowa in the national Envirothon in July.Schools taking part are from: Marion, Northwood-Kensett, Decorah, Montrose, Marshalltown, Red Oak, Paullina, Perry (2 teams), Orient (2 teams), Terril, Winterset, Corning, Fredericksburg and Grundy Center.