Rivers and streams: when not to cross

The force with which water pushes against your legs does not simply grow with speed, it grows much faster. Roughly speaking, physics says: if the water flows twice as fast, it pushes about four times as hard. That is why the difference between “gently babbling” and “flowing briskly” is far bigger than it looks. At the same time the water takes some weight off your body, so your feet grip the bottom less firmly.

The bottom is usually invisible. Stones are covered with slippery growth or roll away, and holes and steps appear suddenly. Cold water, from snowmelt or glacier melt for example, quickly numbs your legs and makes them clumsy. Anyone who falls can get a foot caught between stones or be pushed by the current against obstacles – for example jammed trees that water flows through but a person does not.

Water levels change. After rain or thunderstorms streams often swell quickly and later drop again. Streams fed by snow or glaciers typically carry more water in the afternoon, because the sun has been melting all day, and less in the early morning. So waiting is often a real solution, not an excuse.

The most important work happens during planning. Look at the map to see where your route crosses streams and rivers and whether there are bridges or footbridges. If you would have to cross without a bridge and rain or snowmelt is expected, the trip is unsuitable that day. Plan alternative routes and enough time to be able to wait.

At the bank: stop and look, do not wade in on impulse. How high is the water, how fast does it flow, is it murky, is it carrying branches or debris, how loud is it roaring? And above all: what lies downstream? Rapids, waterfalls, rock steps or jammed trees below the spot make a fall especially dangerous.

There are clear no-go reasons: water above knee height, fast current, murky water, debris, obstacles or drops downstream, if you are alone, already chilled or simply unsure. If any of these apply, do not cross. Group pressure is often the biggest trap here – “the others got across” is not a safety argument.

Floodwater and flooded roads are off-limits, on foot and by car. Even a little fast-flowing water can knock a person over, and a bit more can lift and carry away a car. Under the water the road surface may be washed out, manhole covers may be missing, and debris arrives with great force. The US weather service's rule sums it up: “Turn Around, Don't Drown.”

If someone is swept away, do not jump in after them. Call the local emergency number (112 in the EU), follow along the bank without entering the water yourself and hold out or throw something that floats or a long pole. If you fall in yourself, it is better not to try to stand up in fast current, because your foot can get trapped between stones; the aim is to reach a calm bank as soon as possible.

If a crossing really is unavoidable and the water clearly shallow and slow, cross only at a wide, calm spot, with your pack's hip belt and sternum strap undone so you can drop it in an emergency, with shoes on your feet and poles for support. Never tie yourself to a rope – in the water it can pull you under. Group and rope techniques are learned in a course, not from a text.

Turning back sometimes feels like failure, but at rivers it is almost always the strongest decision. An hour's detour or a night of waiting costs time; a fall into fast, cold water can cost a life. Mountaineering handbooks stress exactly this: the best crossing is often the one you do not make.

Walking barefoot over loose rocks is not a good idea. Your feet get cold and vulnerable, and you slip more easily. If you want to keep your boots dry, you can carry light spare shoes – but only for clearly harmless spots.

In wilderness areas without bridges, river crossings are among the frequent causes of serious accidents. Anyone planning such trips should take a course with a mountain school or alpine club and build in the decision “do not cross” as a normal option from the start.