Scott Kolves of Ephrata was teaching his 10-year-old son to drive when they were on a fishing trip March 30, Grant County sheriff's officials said, citing interviews and evidence.
The man grabbed the wheel when the boy had trouble but couldn't prevent the truck from leaving the canal road near Summer Falls Dam. The truck was swept away in fast-moving water about 30 feet deep.
Nearby fishermen saved the 10-year-old and his 12-year-old brother. Eight-year-old Korey Kolves was found downstream and could not be revived. A funeral for the Columbia Ridge Elementary School second-grader on Saturday was attended by more than 250 people.
Authorities were still looking for the body of Scott Kolves, iFIBER One News reported Monday.
Kolves, 45, worked as a security guard at Ephrata High School and also worked with special needs children.
"Everybody we talk to lets us know how much he loved his sons," Sheriff Tom Jones said in a statement. "Spending time with them - especially fishing - was the highlight of his life. Scott's last outing was centered on the love for his sons and enjoying time with them."
The crash was not criminal, Jones said.
"I again ask the community to refrain from any judgment and to please focus on supportive behavior for the Kolves family," he said. "Please care for the survivors and help them heal from this awful accident."