Rhapsody on River Foam

July 8, 2016
Beached Ducky

River Foam

Guides call it ‘beaver vomit,’ the plumes of brown foam along the river. When you first see the lines of froth, you might suspect foul play and pollution. But long-time Holiday guide Lauren Wood reassured me: “This is the good stuff. This is a healthy river.”


Lauren’s words, as they often do, cajoled me down the rabbit-hole of river research, so I could learn to parse out ‘good’ and ‘bad’ when it came to froth on a river. What I found in that story poked at my basic concepts of Pure Nature and river health. There’s a lesson in the foam.

How does river-foam come into the world?

It’s starts with the shape of water. Some chemistry teacher needs to get out a flipchart with the mickey-mouse shape of a water molecule, and say the electrons in this molecule hang out at Mickey’s chin more than his ears (the two hydrogen atoms). Since opposite poles attract, other mouse-ears are attracted to that chin. We’ll all nod our heads like this makes sense. (Like all good chemistry teachers, they should wait a few years before revealing that atomic “shape” might not be a sensical term, since atomic components may be more like vibrations than foam balls for building Disney characters.)

But the point of it is water clings mildly to water, like self-embrace. That tiny tug bundles small bits of water into spherical drops, and it means the surface of a river grows the thinnest of skins. It’s the background support for 1,700 species of water striders (aka Jesus bugs), skating along a river like they’re listening to Joni Mitchell. (Joni failed to mention in her river-skating song any ‘hydrofuge hairpiles,’ which are the millions of water-repelling micro-hairs that coat the legs and bodies of water striders to keep them from drowning in the drink).

“This is the good stuff. This is a healthy river.”

Pure water remains polar, but a river isn’t the place for pure water: it’s a place of living — and ergo dying — things. All that decomposing funk of the river sometimes makes a natural ‘surfactant,’ which is a term for a substance that fiddles with surfaces. It muddies the boundaries of water. Surfactants are the soaps that allow you to scrub olive oil off a pan, because it lets oil and water mix. On the river, surfactants open water up to the air. Where there’s a riffle, a rapid, a waterfall, the air mixes its way into the water, and out comes foam.


Photo credit: Ajor933, 2007, Public Domain

This particular foam usually isn’t pretty. It traps dirt, leaves, and dead or dying insects. It grows darker brown in time. It might smell earthy or even fishy. Fish and aquatic bugs hide in its shadow from prowling birds overhead.

A healthy spot of foam can be recognized by this very filth. Foams caused by pollution come from detergents and soaps released wrongly into the watershed; the tell-tale sign of this bad behavior is the foam’s pleasant smell — like perfume — and its tendency to remain bright white.

“…beaver vomit is a reminder that purity isn’t always a friend.”

So I’m going to stand at this pulpit and preach one sermon on ‘beaver vomit.’ The foam tells us something about the health of imperfections and dirt. Water clings to itself because the water molecule is bent, lopsided. A perfect molecule would have no tension to hold up skating Jesus bugs. And a healthy river is one loaded with its share of death and decay.

We speak of Nature and Wilderness in terms of Purity, but beaver vomit is a reminder that purity isn’t always a friend. While we try to scrub the world clean we’re liable to release frothing soap that actually wounds a waterway. It’s akin to the story of those tiny plastic ‘microbeads’ in exfoliating face-washes, that jetted their way through wastewater filters and straight into rivers. Our clean-scrubbed faces meant 8 trillion beads dumped daily into waterways, turning rivers and oceans to plastic, swallowed by fish, leaching toxins all the way up the food chain. All for the feel of being really, finally clean.


The river holds its own hopes for new stories, which maybe aren’t far off from the old stories. After all, in the old Hans Christian Anderson fairy tale, before Disney bent everything to happy endings, the Little Mermaid fails to win the heart of the human prince and decays into sea foam.

A sad and brutal story, it’s true. But even still, some off-kilter imaginations might be more sparked by the possibilities of filthy, free-running foam than the tidy life of a pretty princess.

Kate Savage Blog WriterWritten by Kate Savage, desert wanderer, river lover and freelance writer.  Check out Holiday’s River Currents blog for more of Kate’s writing soon!