Almost every evening at this time of year, the concrete and granite embankment along the river at Saco Island is lined with people fishing, and I’ve seen a few folks snag some pretty spectacular trophies there. Although I don’t fish myself, I do enjoy the anticipation of waiting until someone gets “The Big One,” and being a spectator at the moment of triumph.

Aside from that, though, the river itself usually offers something to observe and enjoy. It can be the cormorants coming in for a landing on the rocks just below the Falls or seagulls circling as they wait to feast on whatever the current provides. It can be the reflection of the sun’s light on the water as it sinks behind the old mill buildings, or the rapids just west of the Main Street bridge thrashing and tossing after a period of heavy rain when the level is high and the current strong.

The visual profile of a river changes constantly, with no two ripples or eddies being quite the same. Like all bodies of water, salt or fresh, rivers are restless sources of energy, calm one minute, churning the next. One day, the water level is low, exposing the rocks mid-stream, the current flowing along peacefully as though it had not a care in the world. Another day, with water levels obviously higher due to rising ocean tides or heavy rainfall or snow melt, the river displays its darker side in the form of a churning current and a roar not unlike that of distant thunder.

On one recent evening, the flow of water over the dam was still quite intense at day’s end, and the froth produced by the cascading falls was considerable. Farther down toward the bridge, the thick accumulations of bubbles and foam morphed into narrower shapes that spun and swirled on the water’s surface before thinning and then dissolving at the lower rapids given shape by the submerged boulders.

The white foam is the result of several different natural processes, not the least of which is that the narrower bands of froth are what’s left once the water that thundered over the falls has, in essence, calmed down. The larger bubbles give way to smaller ones until they appear as nothing more than splashes of white paint on the water. While pollutants can produce scum, the foam is more often than not a byproduct of organic matter that has decomposed in and along the river producing what is called DOC, or dissolved organic carbon. As organic materials decompose in water, they release gases that produce bubbles. If this foam contains the residue from dead trees, the foam can appear brown from the tannins in the bark, or it can take on a greenish tinge from algae or decomposing vegetation. Sometimes, the foam forms large puffs in areas where it gets trapped by some obstacle such as a fallen log or branch or when the water level drops and the it gets hung up along the river’s edge.

Aside from the science of it, the presence of river suds provides an interesting means by which to observe how a river’s water moves. At first glance, the river water may seem to be moving along as one uniform body. At certain angles of the light, smaller ripples become visible. But it isn’t until something decides to hitch a ride on those ripples that their actual movements become more obvious.

Along a certain section that seems to be moving smoothly, hundreds of individual swirls and eddies appear that all seem to be turning independently of each other. A swath of foam flows and narrows, then suddenly, its edges start breaking away and twirling in the small mini-currents produced by the energy propelling the entire river forward.

If enough of those larger tear-drop-shaped foam swirls appear on the river, it is almost like looking down at a large piece of fabric with a paisley pattern. Only in this case, the fabric is alive and constantly changing as each shape disperses at the river’s whim.

Like those blown by a child on a breezy day, the river’s bubbles show us its playful side. How quickly, though, that personality can shift, causing us to heed always the powerful force that lives inside each swirl, each curl and whorl of a river’s majesty.

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