An anchoring device for a self-propelled irrigation system includes a screw pile and drive assembly that drives the screw pile into the ground to anchor a drive tower of the irrigation system to the ground. The screw pile is rotatably driven about a vertical axis and movable vertically relative to the drive tower. The drive assembly can include an electric motor with a suitable gear reduction that causes the screw pile to be rotated slowly with a large amount of torque. The drive assembly can be mounted stationary to the drive tower, or it can be mounted on tracks so as to move vertically together with the screw pile. A low voltage electrical system with one or more batteries can be used to power the electric motor. A solar battery charger or other charging system can be used to maintain an electrical charge in the batteries. A controller is provided to activate the drive assembly when adverse weather conditions are detected, or upon receiving a remote command from the operator.