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

• Wear a life jacket.
• Try to avoid entering the water. If you must enter the water to survive, do it slowly. If experiencing cold shock, hold onto something until breathing settles down.
• Keep your head, neck, and face out of the water.
• Get out of the water as soon as possible. Climb aboard a boat or on top of an overturned boat if you are unable to right it.
• Do not attempt to swim for shore if it will cause greater exposure to the cold water and there is a good chance of being rescued.
• If there is little or no chance of rescue and the shoreline is a reasonable swim away, swimming to shore may be the safer option.
• Assume the 'Heat Escape Lessening Position' (H.E.L.P. or Huddle) to protect the core organs. While floating in a lifejacket, draw your knees together toward your chest and hold your upper arms tightly to your sides.
• Remain as still as possible. Excessive movement in cold water cools the body much faster. Thrashing flushes away the water warmed by the body.
• Clothing provides some protection against heat loss, especially a waterproof outer layer. Don't remove clothing—it can benefit you by trapping water warmed by the body's heat and keeps it near.
• Carry survival gear including a blanket, hat and extra dry clothing on board.

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.