Held over two days in May each year, school groups, teachers, parents and individual citizens participate in river clean ups throughout the county. Volunteers focus on clean up (litter and invasive plant removal) of a particular stretch of waterway, or lead an educational session for students on local plants, animals, birds, trail building or other natural history subjects. For information, contact Claudine Rehn at the TEP office: (503) 322-2222.