South Jordan resident Adrian Jackman, who was driving the motorboat, veered at the last minute but still struck the front corner of the houseboat, Alldredge wrote. The motorboat overturned with 13 people on board, including seven adults and six children, who were on a family trip from the Salt Lake City area.
Adrian's 57-year-old wife, Marilyn Jackman, died; Marilyn's 22-year-old daughter Jessica Jackman, and Valerie Rae Bradshaw, 29, of Sandy, were missing in the water.
Other individuals on the motorboat suffered minor injuries.
Adrian Jackman and his 11-year-old granddaughter were flown to a hospital in Flagstaff, Ariz., where they were expected to survive. Another person was transported by boat and then by ambulance to the Page, Ariz. hospital.
All of the children were wearing life jackets. No one on the houseboat was injured.
The National Park Service, Utah State Parks and Kane County Sheriff's Office were working to find the missing victims and to investigate the accident.
A National Park Service dive team on Friday used a robot with a camera to search the area, but technical problems ended the effort shortly after 2 p.m.
Meanwhile, a Utah Department of Public Safety dive team was due to arrive as early as Friday night, bringing with them a "side scan sonar" to search for the missing victims.
The water is about 400 feet deep at the crash site, Alldredge wrote.