Cold water is extremely dangerous. It quickly robs the body of its strength, diminishes coordination and impairs judgment.
"Immersion in water as warm as 50-60 degrees can initiate what has been determined to be "cold water shock," said Liz Lodman, Montana Fish, Wildlife & Parks boating coordinator. "When a paddler capsizes and is immersed in cold water, the body's first reflexive action is to gasp for air, followed by increased heart rate, blood pressure and disorientation. The shock can even lead to cardiac arrest in susceptible individuals."
Without proper equipment and apparel, the body is incapacitated within minutes.
A second dangerous situation that can occur in cold water or cold weather is hypothermia. Hypothermia occurs when exposure to the elements prohibits the body from reheating and maintaining its core temperature. Typical symptoms of hypothermia include: shivering, impaired judgment, clumsiness, loss of manual dexterity and slurred speech.
"Many water bodies are fed from high mountain springs in our state and don't get above 65 degrees even in the summer," Lodman said. "That makes cold water immersion and hypothermia a particular threat to paddlers in Montana."
To respond effectively, it is important to understand the body's reaction to cold water.
Stage 1: Cold water shock
This response begins immediately upon immersion and peaks within the first 30 seconds to 5 minutes. Breathing changes are immediate and may include an involuntary gasping, rapid breathing, dizziness and confusion, resulting in water inhalation and possible drowning. Circulatory changes include a sudden rise in heart rate and blood pressure, possibly resulting in stroke or heart attack. Wearing a life jacket greatly reduce the chances of water aspiration when a boater dumps.
Stage 2: Swim failure
After being in cold water for three to 30 minutes, it becomes increasingly difficult to swim or move. The nerves and muscles in the arms and legs cool quickly because of the constriction in blood flow. Manual dexterity, handgrip strength and movement speed drops by 60-80 percent. This limits the victim's ability to assist with their rescue by catching a rope, putting on a life jacket, or climbing a boat ladder.
Stage 3: Hypothermia
Someone who survives the first two stages of cold water immersion faces hypothermia. The continuous loss of body heat eventually decreases core body temperature and can result in death. A person wearing a life jacket can survive for hours. The life jacket increases their chances of being found and rescued.
Stage 4: Post-rescue collapse
Even after their rescue, a person is at risk. During the process of hypothermia, the vascular system becomes ineffective at moving blood. The result, when the body tries to rewarm itself, can be a huge strain on the heart. Handle cold water immersion victims very gently and seek treatment by a knowledgeable medical team for transport to a hospital.
Surviving Cold Water Immersion
For more on staying safe in the outdoors, go to the FWP website at fwp.mt.gov on the Recreation page, click on Stay Safe Outdoors.