Why is getting caught in a backroller near a low head so dangerous?

Getting caught in a backroller near a low head is dangerous because the strong current created by the water flowing over the obstruction can pull individuals underwater, making it difficult to escape. The backroller can trap a person against the obstacle, leading to potential drowning or injury from the force of the water. Additionally, the turbulent water can disorient swimmers and limit their ability to find a safe exit. These factors combine to create a highly hazardous situation for anyone caught in it.