Crossing a stream or creek is often a part of mountaineering approach hike, and it’s potentially one of the most dangerous parts of the climb. Here are a few tips (gleaned from several whitewater rescue courses I’ve taken) that can make this a bit safer.
Take some time to scout. Send some people upstream or downstream to look for a friendlier crossing if you don’t like what you see when you first arrive.
Snowmelt streams are usually lower in the morning. Consider in early morning crossing to have lower water levels.
Water depth rule of thumb: if the water is moving fast and over your knees, you should take extra caution. Note that this rule does not apply equally to taller/shorter team members, and the speed of the water has a great affect on the potential hazard of the crossing.
Always face upstream.
Using poles (trekking poles or sturdy sticks), one in each hand, is the single best way to improve your balance in a crossing. Not enough poles for everyone? Toss them back once one person is across.
Cross in a three person triangle – Moving in unison across the creek as a group can add stability to everyone. Make a triangle, with the “point” being the largest person, who faces upstream. The point person has a pole in each hand. The other two members of the triangle have a pole in the outside hand and one hand on the shoulder or pack of the point person. The larger point person makes an eddy of sorts with the their legs, providing an area of slack water for the inside legs of the two back people. If the back people start to slip, they can grab the other members on their triangle and hopefully recover.
Remove your pack waist belt so you can quickly ditch your pack if you fall in. On a really challenging crossing, you may want to completely remove your pack. Have another stronger person carry it, or maybe rig a clothesline loop rope across the creek and ferry the packs across one by one.
Try to find a crossing point that has a friendly runout; if you were to lose your footing and fall in, you’re not going to be swept over a waterfall, or into dangerous rocks or a log jam.