It appears that not all that stinks in a river is sewage! This is such useful information I have reproduced it here…
In response to a fb post in ‘St Dogmaels Positive People Posts’ on 22-Dec-22 which was follows:
“My most positive hope for the New Year is that sulphurous PONG that hangs over the village and Cardigan again today gets identified and dealt with before more harm is done. If you have any clues, message me, please.
Piers Partridge replied …
“In reply to St Dogmaels Local Producers’ Market, I’ve been looking in to this and, Yes, it’s a distinctly gassy smell, but probably not methane which is odourless. We’ve been getting this smell when there have been no sewage releases so it is also probably not sewage. Most likely it’s Hydrogen Sulphide, which has the classic rotten egg smell, and is coming from agricultural slurry, or waste. The gas is heavier than air so will travel downhill and settle on the river bed. People then think the river is the source of the smell, which confuses the issue. My reading suggests that there are certain modern bedding additives and food supplements given to cattle which change the chemical makeup of slurry and if not managed properly can create the release of Hydrogen Sulphide.
It’s not harmful to human health if you can simply smell it, but being able to ‘taste’ it, as some people have reported suggests it is above safe levels. Please message me if you experience that or any other information you might have.”
Many thanks to Piers for his research into this.