The mass die-off of fish in York could have been caused by raw sewage pollution, councillors said today.
As YorkMix reported last Thursday, hundreds of dead fish were seen floating in the Foss last week.
The Environment Agency said they believed the problem was caused by low oxygen in the river due to the heat and atmospheric conditions – but it didn’t rule out a pollution incident.
Meanwhile, Yorkshire Water dismissed the idea of a sewage discharge, saying it had tested the Foss and found “found no ammonia present”.
Now though, councillors now believe it could have been a pollution incident.
The council’s joint executive member for environment and climate emergency, Cllr Jenny Kent said: “This is obviously a greatly concerning incident. We want to identify the cause and see what can be done to prevent a reoccurrence.
“We’re very fortunate to have scientists locally at the University of York who the previous Tuesday afternoon happened to be monitoring the river for nitrates and other chemicals in the water, shortly before the first reports of the fish deaths.
“The York team sampled five locations along the river between Sheriff Hutton and the city centre.
“The site at New Earswick footbridge smelt strongly of raw sewage and the water contained nitrate levels 80 times higher than seen at the Sheriff Hutton site. Levels of nitrite and ammonia were also elevated. Nitrate levels then declined at the downstream sites.”
Her fellow executive member, Cllr Kate Ravilious, added: “This indicates that the discharge of untreated sewage cannot be ruled out as a cause for the fish deaths, something the River Foss Society has confirmed as being responsible for previous significant fish deaths in the Foss.
“And of course this incident won’t just have impacted fish; it will have damaged the entire river ecosystem.
“The scientists are awaiting results on the levels of pharmaceuticals in the river; if levels are high it would add to the evidence for sewage discharge. We’re really grateful for Professor Boxall and his team for sharing their results.”
Councillors say once the full results are back, and if untreated sewage discharge is confirmed, they will be pressing Yorkshire Water and the Environment Agency for a meeting to discuss the issue as soon as possible.
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