What’s the foam on our river?

A little while ago l received some images taken by Bath’s North Parade bridge and showing lots of foam on the surface of the River Avon.

Nick Sommer writes:

There’s been a lot of publicity recently about pollution on the Wye and the lack of action by the Environmental Agency. Given that Bath is such an iconic tourist city, all I can say is that if I was a visitor, I wouldn’t be very impressed by the look of this river and am surprised there’s been no indication by the EA that they are carrying out any monitoring of the water quality.

They may do, but how do they account for all that horrendous-looking foam, which varies in intensity?

The pictures were taken by North Parade bridge and I sent them straight to you. I wish I had taken photos of the “foam-bergs” that floated on down the river beyond Windsor Bridge on the day I saw them.

I took this up with the Environmental Agency – who were keen to know if this foaming was seen downstream of a weir. In this case it was – as the water had flown over the Pulteney Weir.

An Environment Agency spokesperson said: “Foaming can occur in the natural environment when the surface tension between air and water is interfered with by fatty acids and other chemicals, creating a thin film. This film can trap bubbles caused by turbulence and agitation in the water and become foam.

Large amounts of foam can accumulate in certain areas of the river, especially downwind and within eddies, or just downstream of turbulent water, for instance below weirs. This foam is usually harmless; in fact only about 1 % of the foam is made up of the foaming agent which is usually a naturally occurring fatty acid. Most of the foam is simply air and water.  

However, foam caused by synthetic products such as detergents, may be a sign of pollution that is harmful to fish and other aquatic life. It is difficult to identify what type of foam it is without any accompanying impacts like dead fish or its proximity to structures like sewage treatment works or weirs.“

The Agency is keen to emphasise the need for reports of suspected pollution to come in via the telephone.

“Our operators know what questions to ask to gauge the severity of a pollution and can request an inspection if warranted. Plus we can cross-reference with any discharges within the vicinity.

If you suspect a pollution event inform the Environment Agency as soon as possible using the incident hotline 0800 80 70 60 (24 hours).”