When I am out fishing, I will take notice of bubbles or foam lines on the rivers and creeks. Foam is often seen next to the banks of streams, or on windy days, foam can be seen along lake shores. What is foam other than small bubbles in the water? What causes the formation of foam in our rivers and creeks? Why should we fish a foam line?
The occurrence of foam happens with variations in the water surface tension and the physical presence of air. There is a slight tension on the water surface caused by the chemical attraction with water molecules. This tension allows some insects to move along and on top of the water surface.
There are certain molecules that interact with water and reduce surface tension. These molecules are called surface active agents, or surfactants. Foam is produced by air being introduced within the turbulence of river riffles, at the bottom of waterfalls, and waves breaking along a shoreline.
Organic surfactants are part of a large variety of plant material such as algae, grass, stems, leaves, sticks, and nearby contributing watersheds that when dissolved in water, are called dissolved organic carbon. With the presence of dissolved organic material in lakes and streams, this usually creates darker in color water, particularly with springtime snowmelt. The fall season is another time with dissolved organic materials with leaves falling into lakes and streams. These conditions produce foam and supply energy and many other benefits that are important to the aquatic ecosystems.
Foam from plant produced surfactants will accumulate in concentrations against banks, logs, and rocks. It is white in color and will transfer into brown over time as sediment particles build up in the foam. The foam will magnify for a period of time and gradually deplete in size. Foam abundance can be often seen after a rainstorm which transports surfactants to the rivers and creeks as well as lake shores on windy days.
Foam will show in details of the insect life in the river. Patches and trailing foam lines consistently have dead insect life adhering in its structure. Trailing foam lines may give a sense of safeguard to the trout to venture for food sources in faster, open water. The foam lines are where “foam is home” and a trout nose may show through while eating trapped forms of food within the foam. Cast into those trailing foam lines!
It doesn’t matter the time of year, or which river, lake, creek you are fishing. Observing foam is essentially a key to success whether it is fishing flies, emergers, or nymphs. See you on the river.
CHECK OUT OUR MOST POPULAR POSTS
Fly Tying Tutorials With Togens
How To Collect Throat Samples
Lets Talk Hooks
Reading The River
We are always expanding our catalog, checkout what's new in the shop!