Foam and Foam Lines

​​​​Foam and ​​Foam Formation

The release of dissolved organic matter from the decay of plant and animal material is the primary source of naturally occurring foams. Persistent foam bubbles are a result of these compounds reducing the surface tension of water in the same way the soap does. These natural surfactants are made up of carboxylic fatty acids derived from plant lipids, lignins from wood, bits of protein and dissolved organic matter. Generally naturally occurring foams are non-toxic, short-lived and become a brownish colour as they age.

Foams can also be produced by man-made compounds. Compounds such as detergents, shampoos and weedkillers can cause the formation of foam. Foams that are due to man-made compounds tend to remain white in colour, break down rapidly and are likely to appear close to the original source. Synthetic foams have the potential to be harmful to the aquatic environment.

In rivers and streams the flow of water results in the formation of foam. In lakes and dams, it is the wind that agitates the water surface and results in the formation of foam. In estuaries wind also results in the formation of foams as do the currents associated with tidal movement.

Wave action in the marine environment contributes to the formation of foam through the agitation of seawater. Sea foam or spume as it is commonly termed occurs worldwide and varies in extent due to location, surrounding marine, freshwater and or terrestrial inputs and prevailing climatic conditions.

Fo​​am Lines

In streams and rivers the foam bubbles tend to accumulate and form foam lines where areas of different flow meet, such as at confluences of streams, in eddies or below waterfalls. In lakes, foams lines tend to be a result of prevailing winds rather than water currents and commonly form 'windrows' which accumulate on the windward shoreline.

In estuaries and marine environments flow lines tend to be a result of converging tidal currents, river outflows, wind action or a combination thereof. Wave action also contributes to the formation of foam through the agitation of seawater. The extent of a foam line is dependent on the prevailing weather conditions

Issues relatin​g to foams

Should you have concerns relating to foams in your area, and,

If urgent

Contact the EPA Incident Response Hotline 1800 005 171, or email to

Or if non-urgent

Email to​​