Watertown Fire Rescue responded at about 2:30pm to a grass fire near Cottonwood Slough.  The fire was burning towards a large pile of trees and a shelterbelt when crews arrived.  WFR called for mutual aide from Florence Fire Department to control the blaze.  The fire was controlled before getting into any structures.  Crews were on scene for about 4 hours.  In total about 40 acres burned.