 The other five were flown by life flight to St. George. The source of the carbon monoxide is still under investigation, but this marks the third carbon monoxide-related incident responded to by Glen Canyon National Recreation Area Rangers. Officials advised anyone on a houseboat to have operating carbon monoxide detectors on board at all times. Of course, symptoms of carbon monoxide poisoning include headaches, dizziness, nausea, vomiting, and confusion.