Foam on rivers, lochs, and coastlines
What is foam?
Foam is produced when substances in water interfere with the surface tension of water allowing air to become trapped in stable bubbles and create foam.
Where do these substances come from?
These substances can be produced naturally or result from human activities:
- Natural - produced from decaying organic material. They are abundant during autumn when aquatic plants and algae begin to die and trees drop their leaves.
- Human - including both natural and synthetic substances. They enter the water from point-source pollution (e.g. fire-fighting foams, detergents, sewage and tanneries) or diffuse pollution such as farming run-off of pesticides, slurry etc.
How can I identify foam types?
Natural foams may begin white in colour but often become quickly discoloured by sediment and organic matter, turning them shades of brown or green.
Natural foams usually accumulate in sheltered areas and eddies after periods of heavy rain and high winds. They have an earthy odour, possibly fishy or grassy. Foam from decaying algae may be slightly green in colour and is commonly located on the shores of large water bodies or at the coast.
Foams from human activities typically remain white in colour and have a perfumed or soapy odour.
They usually occur over a small localised area close to the pollution source and are unrelated to natural events such as high water flow or windy conditions. The substances involved may also have other environmental impacts such as harm to fish or amphibians.
How do I report pollution related foam?
Report environmental events online or by calling the pollution hotline on 0800 80 70 60.
Including photos and providing a detailed description of what you can see will help SEPA with the response.