Foam line

Most foam is very light, white to start with, often turning brown after a period of time if sediment builds up and forms discernible lines as individual mats accumulate.

It is thought that the foam lines on the water freeze at night with the current causing repeated collisions against each other to eventually become circular with a distinct rim.

Brown-water streams with brown water contain high levels of DOC and much of the foam forms after snowmelt, after prolonged heavy rains and in autumn.

[3] The reduction of effluents from wastewater treatment plants and the introduction of biodegradable detergents have greatly reduced the incidence of pollution-related foam, the presence of which can be ascertained by a fragrant or perfume-like smell.

[3] Stillborn, emerging and drowned terrestrial insects progressively accumulate within foam lines in summer, trapped and held in place by the surface tension of the bubbles within.