A tower for a mobile-tower agricultural irrigation system such as a pivot irrigation system using multiple towers to carry a water supply pipe and sprinklers over a field. The tower includes a fender overlying the wheels or other ground-engaging elements of the tower. The fender may project in widthwise directions transverse to the track travelled by the tower, and serves to deflect water discharged from the sprinklers away from the track travelled by the tower, so as to minimize formation of ruts in the track. The fender desirably is disposed at a height above the field such that the fender can pass over a crop growing in the field. The sprinklers disposed closest to the tower having the fender may be disposed at a height well above the fender, whereas other sprinklers further from the tower may be disposed at lower heights.