RedactedNarrative: V1 was travelling south on the colorado river near the center.  V2 (a kayak) was travelling south, also near the center of the river.  V1 came around a smaller rock bar/island and did not see v2 until the last minute and panicked.  
  
  V1''s operator pulled the lanyard, cutting power to the jetski, causing him to lose power and strike the back of the kayak.  
  
  The kayak occupant was knocked unconscious and thrown into the water.  The passenger of v1 jumped into the water to get the unconcious kayaker and dislocated his shoulder on impact with the water.  The operator of v1 was uninjured.  Both the kayaker and the passenger of v1 were transported to the hospital, where they were treated and released.