A waterjet safety enclosure formed by walls using a detection device or light curtain to detect unsafe conditions. The waterjet safety enclosure walls can be used in new work areas or retrofitted and shaped to fit existing work areas. The waterjet safety enclosure walls may form a partial or complete perimeter about a work area and may be adjustable or mobile. The waterjet safety enclosure wall detects unsafe conditions when a high pressure stream of water from a waterjet cutting machine approaches, contacts or penetrates the waterjet safety enclosure wall. The detection device detects the high pressure stream of water and sends a signal to a controller to stop the operation of the waterjet cutting machine.