RedactedNarrative: On September 29, 2017 operator was driving his pontoon boat north on Cheney reservoir with five passengers on board. The vessel was traveling at approximately 10 mph when it struck an underwater concrete obstruction with the port pontoon. All five passengers were thrown to the floor of the vessel and operator hit the steering wheel. Two of the passengers stated that they were looking for the danger buoys marking the obstruction, but did not see it until just prior to impacting the concrete. The prop was also damaged during the accident. One subject was suffering from ankle pain believed to be a result of the accident and saw a doctor on October 10, 2017, but did not report an injury.