Updated: Aug. 31, 10:26 a.m.The state director for Rep. Denny Rehberg (R-Mont.) remained under close medical supervision Saturday, several days after suffering a “significant brain injury— in a boating accident in Montana that sent him, the Congressman and three others to the hospital.“It’s a significant brain injury, but it’s being termed as survivable and it’s probably not going to require surgery,— Erik Iverson, a former Rehberg chief of staff, told the Flathead Beacon on a conference call Saturday. “They’re keeping him sedated as doctors monitor the pressure on his brain.—Rehberg’s state director, Dustin Frost, like the four others involved in the crash, was listed in stable condition.Rehberg had surgery to repair a broken ankle and a fracture around his eye on Friday. Rehberg’s blood alcohol level was measured at the Kalispell hospital, registering .05, below the legal limit of .08.State Senate Majority Whip Greg Barkus, his wife and Kristin Smith, Rehberg’s deputy chief of staff, were also in the crash. Rehberg and Smith are expected to be released from the hospital on Monday, Iverson said.Reports said Barkus was driving the 22-foot boat when it crashed into rocks on the shore of Flathead Lake around 10 p.m. Thursday. Campers at a nearby park heard the crash and called park officials.Jim Satterfield, regional director of Montana Fish, Wildlife & Parks, described the incident as “a serious boating accident.—Three people on the boat were flown by helicopter to Northwest Healthcare in Kalispell and two were taken by ambulance; Satterfield could not confirm how Rehberg was transported.Satterfield said investigators would look at a variety of factors, including the speed of the boat, the condition of the boat, whether people were wearing life jackets and whether alcohol or drugs played a role.“Those are common in any accident investigation,— he said.In 2004, Rehberg was in a horseback-riding accident while leading a Montana group on a trade mission in Kazakhstan. The incident, which involved Rehberg falling off his horse and getting stepped on by another horse, became the subject of controversy after some alleged he was drunk at the time.Jennifer Bendery contributed to this report.