Monday, November 2, 2009

Crossing streams

The Washington Trails Associattion (Website) included an article about how to Ford a river in the September-October 2009 magazine to members (found on newsstands). Well, after 14 years of field experience wading and measuring rivers and another 14 as a hydrologist and even more as a fly-fisherman, I found the advice has some flaws, some serious ones in fact. So I wrote the editor (Laura Lunney) a letter, which was subsequently published in the Novembe-December magazine.

And so folks don't necessary have to buy the issue to read the letters, here is what I wrote.

Dear Ms. Lunney,

I read the monthly issue of the WTA religiously and this month was no different. But I have to take issue with the article, "Ford a River", about fording a creek or river. For reasons I don't understand, myths about fording a river persists in the recreation and hiking community, and was repeated in this article.

And my complaints?

Well, for one, any hiker will never encounter "laminar" flow in any creek or river. It's almost always turbulent flow. The information about the cross-section and vertical differences in the velocity are correct, kudos to the author, but I wouldn't consider it a univeral rule. You have to understand the creek or river.

I will provide the practice as used by the USGS with their streamgaging technique measuring rivers.

You should pick the widest place with the most consistent depth that you can see, which are usually found in reaches between curves or bends in creeks or rivers. Never wade across a cut bank, the opposite bank is where the deepest and fastest will be and together too (see factor below).

Always face the opposite bank keeping your body parallel to the flow. This puts all the water against your upstream leg. It's harder but you have both your other leg and your wading rod to make yourself a tripod.

This is where the myth of facing the flow is wrong and doesn't give you an out if you lose your balance except falling over. Being parallel provides the balance in the back leg/foot and stick.

Keep the weight of the pack over your hips which means leaning forward a little. It's about being centered over your feet.

Always put the wading stick ahead of you and about the same level as your downstream foot. Make sure it's secure against the bottom and can hold your weight.

Then you can shift the upstream foot and then the downstream foot, and then the rod again. Always secure your foot with each move so it can, if necessary, hold you against the flow.

You want to always maintain balance with your feet, the wading rod is extra for stability and let's you move each foot.

The John Muir rule (for me), rest going across if necessay. Standing in the middle of a river is nice and you can catch your breath, balance, energy and focus.

Keep you eyes on the opposite bank and upstream ahead of you. You're looking for changes in the flow conditions, both depth and velocity.

Personally, I would never recommend loosening the pack. It's part of your weight distribution. I would release chest clip between the shoulder straps and know how to release the belt quickly. My view is that you don't want anything shifting on your back and changing your balance.

The rule of thumb is that most people can wade a stream factor of 6-8 depending on your size, weight and fitness. This factor is the deepest depth times the fastest velocity (eg. 2 foot depth times 4 feet per second is 8). This would be the upper margin for a normal person with a pack. The USGS used a factor 10 but we didn't wade with backpacks.

The velocity can be determined with the obvious object floating in the river in several places in the cross section. Sticks do nicely. Depths are harder but you can estimate it reasonably well in many cases. The point is that if the number is too high, find another place.

Another rule of thumb is don't wade when it's too far above your knees unless it's slow (3 feet per second or slower) or you have experience wading. This is important if you find the depth increasing near the middle of the stream.

If your feet begin to move underneath you, common with moving bedload, don't lift your feet, slide or waddle to find a secure place or across the stream. If you must, start moving downstream.

Don't wade around boulders, the flow around them is usually faster and deeper above and below the boulder. If you have to wade across a boulder stream, always wade above the boulder. The flow around over and below often scours holes below.

Whatever you do, if you get stuck, just backup like you went forward. Do not turn around, period. Always keep your body parallel.

If it's a high elevation (snowfed) stream, remember if the streamflow was low in the morning, it's likely to be higher later in the day from the diurnal (upstream snowmelt).

If you plan to cross a number of streams, consider wading cleats (simliar to crampons but for rivers) or lightweight fishing boots with non-slip soles. You can always stash them when across and pick them up on the way back.

Otherwise the article was typically excellent. And for what's it worth, all my experience was from 28 years as a hydrologist with the USGS, half in the field measuring a lot of streams and rivers (OR, AZ and WA) and fly-fishing more streams (CO, AZ, OR and WA). And we had chest waders or hip boots and cleats.

Take care and keep up the great work.


To this letter I can add that over those 14 years I never lost my balance or fell in a stream or river. There were some critical moments and times wading rivers, even a few what I call John Muir moments, where I couldn't go forward and definitely couldn't go backward.

The river had either pinned me in the spot and flowing around me with a good velocity, like a boulder, or the bed was moving under my feet and either moving me downstream or causing me to sink. And if you have ever stepped in a deep pothole in a river, like I've done more than once, you realize just how stupid you are when you can't get out of it.

Anyway, I don't know if my experience will help. I wrote the letter to address the serious errors in the article, any of which would cause you to fall in the river. And since it wasn't mentioned, if you do fall in and are carried downstream, follow the advice of river rats, which is move to sitting position with your feet pointed downstream and look for a place to swin to the shore. And above all, hope and/or pray.

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