RedactedNarrative: The operator was pulling his daughter in a tube when he struck a rock bar in the Greensferry Bay of the Spokane River. The operator then attempted to start the vessel, as he was attempting to start the vessel a bystander in a pontoon secured a tow line and began towing them to their destination which was Blackwell Island approximately two miles upstream. The operator then turned on the bilge pumps to make sure the vessel was not going to take in water. While undertow the operator realized the vessel was taking in water and called 911 while he attempted to remove water from the hull of the boat with a bucket. Approximately one mile from the intended destination is when we got on scene in which we advised the operator to get onto our vessel in which I jumped onto the pontoon boat which was beginning to struggle with the weight of the water filled vessel and I cut the line. In which the vessel was secured on shore and recovered by Lake City Marina.