P12-200-2929NA Klamath Project - Oregon-California. View of small crawler tractor being used to backfill the open trench. Excavated earth, windrowed along the open trench, provides the material needed for the backfill. The backfill is not compacted after it is pushed into the trench. However, it is mounded over the trench to provide for future settlement; November 1972; Bureau of Reclamation photo by D. W. Stein