While the cold weather has impacted rescue crews efforts to find the bodies of two people believed to have drowned in the Big Sioux River, low temperatures can actually play a helpful role in potential drownings.
That's because of what's known as the diving reflex that's triggered by cold water.
While the situation at Falls Park is grim, sometimes the cold weather can lead to a bright outcome in potential drownings.
"Because you do have the protective reflexes and the rapid cooling, so that protects the body from end-organ injury for a longer period of time," Sanford Emergency Medicine Dr. Robert Harms said.
Harms says when a person is suddenly immersed in cold water, the muscle that controls the opening of the throat closes. That prevents a person's lungs from filling with water. Other reactions in the body allow a person to survive longer without oxygen.
"The body metabolism cools very quickly, so heart rate slows and body temperature and metabolism slows, so there's actually some protection of the body," Harms said.
Harms says in unusual circumstances people have lived one to two hours immersed in freezing cold water.
Compare that to warm water when a person can drown in less than five minutes.
"Most resuscitations have to occur within five to ten minutes in a warm water situation," Harms said.
But Harms says whether the water is cold or warm, anyone can drown, even the best swimmers. In fact, cold water causes a person's muscles to get stiff and can hinder your ability to swim.
"Plus the current is likely more rapid than you assume, and the surface underneath is very slick with water and rocks, and it's hard to maintain balance," Harms said.
That's why Harms says even though you might feel like you should try to rescue a person in the river, it's best to leave that duty to people trained for these emergency situations.
Harms says a person's heart usually stops beating within ten to 15 minutes after going under water.