An Iowa agency has proposed fining Adventureland park after an investigation prompted by the June death of a worker at the theme park.

Officials have said Steve Booher was fatally injured June 7 when the Raging River ride started unexpectedly as he was helping people off.

The Iowa Occupational Safety and Health Administration has fined the Altoona park $4,500. The park has 15 days to contest the agency's findings. A park spokeswoman didn't immediately return a call Monday from The Associated Press.

A day after the accident state inspectors reported finding found no safety defects.

But after a lengthy investigation, Iowa OSHA determined that Adventureland should install devices to ensure that ride assistants are positioned safely before ride operators let the boats advance.