Foam is Home

 

Foam is home for hungry trout.

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?

For the love of foam.

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 which interact with water and reducing the 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.  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 created from the rapids and the dissolved organic carbon in the creek.

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 swirl behind rocks.

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 many times, a trout nose may show through while eating trapped forms of food within the foam.  Cast into those trailing foam lines!

Foam with lots of insect life!

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.

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Creekin with success with a beautiful brookie hiding under the foam.