Many SAGD facilities recycle the produced water for use in steam generation. High opacity, coloured boiler feed water (BFW) from recycled produced water makes dissolved oxygen measurement difficult. New sensing technology using fluorescence decay now permits dissolved oxygen measurement that is unaffected by these conditions. Membrane based dissolved oxygen meters frequently fail in those conditions. Dissolved oxygen levels of 2 ppb were monitored for 6 weeks continuously where it was not previously possible with other techniques. A membrane based instrument was rendered inoperative after 2 days in the same service. In another facility, a 113 ppb oxygen decrease across a heat exchanger from active corrosion was detected. In this presentation several case studies will be used to outline where dissolved oxygen measurement assisted in facility operations, preventing costly maintenance and loss of equipment.