Hazards amplified in spring runoff

  • Published
  • By James Biesel
  • 341st Services Squadron
MALMSTROM AIR FORCE BASE, Mont. --  There is a lot of water, but that is why people want to go! It's not dangerous, it's just water! 

Many people get their experience on rivers during normal flows, when air temperatures are hot and the water temperatures are warm. Before venturing onto a snow-melt swollen river for an adrenalin rush adventure, consider other factors before launching (the point of no return). 

- COLD WATER: Recently, the water in most Montana rivers was 32⁰F. Couple that with the fact that water steals heat from the body 25 times faster than air. Water also robs the insulation of its ability to protect you from the cold. A swim can be fatal because hypothermia sets in quickly. 

- SHOCK: Suddenly being tossed from the security of a raft or canoe into freezing, turbulent water requires a lot of discipline to hold off panic in order to effectively deal with the crisis. The first major challenge is to breathe, exhaling first because the shock of hitting the cold water instinctively causes a person to suck in a huge gasp of air. 

- POWERFUL FORCES: The force generated by tons of water rushing down a river is beyond the imagination of most people. Most have experienced water spurting from a shower head or garden hose. Most have seen TV footage of rioters blown over by a water cannon, but few have experienced the power generated by the current of a river. More than likely, anyone getting pinned against a rock, river bank, or strainer will not be strong enough to free themselves. Powerful forces also accelerate the demands to maneuver the raft and make them less responsive to paddle or oar strokes. 

- DEBRIS: As stream flow increases, the branches and trees that have fallen throughout the year are swept downstream along with trees that fall as banks are eroded from underneath. Trees and branches tumble making them hard to anticipate. When lodged, trees and branches form strainers that can pin a swimmer under water. Note: strainers can also be created as high water pushes through submerged fences and gates. 

- UNDERCUT BANKS: Rock walls are frequently more eroded lower down where water flow consistently chips away all year. When heavy flows come, a swimmer may be pushed into the "undercut" and pinned. These hidden hazards also present challenges to boat handling, as the major stream current isn't deflected at the surface and a pillow doesn't form to help turn the boat, increasing the probability of a flip right at the spot swimmers could be pinned in the undercut. 

- HOLES and DAMS: Dams and holes have a strong upstream flow. The heavier the downstream flow and the farther the drop, the upstream flow becomes stronger, more turbulent and more aerated. In the aerated water, a swimmer's personal floatation device often doesn't keep a swimmer's head out of the water. Swimmers also have a hard time escaping a hole. After the swimmer is pushed down by the powerful downstream flow, they are grabbed by the upstream flow as they start to surface, pushed back upstream toward the powerful downstream flow that will start the cycle over again. A low-head dam is useful to create a pool for boating or divert water into irrigation channels, but presents an extreme hazard to those in the river. Often passing over the dam is uneventful, but the surface current below the dam is so strong it pushes the craft back upstream into the heavy downstream flow which grabs the end or side of the boat and flips it. Swimmers are often "flushed out" of a hole, but low head dams are uniform across the river offering no opportunity to break the "recycle." 

- FOOT ENTRAPMENT: When anyone falls down, their first instinct is to stand up. If ejected from a boat or raft, fight the urge to standup. Should the swimmers foot become lodged between rocks on the bottom, the force of the river will hold the swimmer face down. The possibility the victim will be able to self-rescue is remote. 

- COMPOUNDING HAZARDS: Cold water is a hazard in itself. Add that hazard to forces that are more powerful than you, could possibly be harmful. There is an increased possibility of getting ejected or flipped into the river, increased probability of entrapment, the probability of longer swims if ejected or flipped, and lower probability of rescue. This creates a situation that needs to be carefully analyzed before anyone puts a watercraft into the river. Though high water has the potential to be exciting, know your limits and be smart enough to stay on the bank when the hazards are high.