HUNDREDS of fish in a Horwich river were killed because of a ‘short, sharp, shock’ caused by a chemical pollutant, it has been revealed.

An investigation is continuing into how scores of fish were killed in a section of the River Douglas near to Squirrel Lane.

Dog walkers were horrified to find several varieties of dead fish — including brown trout — in the river on Wednesday and Thursday.

The Environment Agency has been investigating the cause of the deaths but says the river should now be back to normal.

A spokesman said: “Fish are very sensitive to changes in water chemistry. In this case we think there was a short, sharp, shock to the fish with the chemical pollutant causing a change in pH within the water.

“The pollutant should have only posed a risk to aquatic life that are sensitive to changes in pH that were about in the immediate vicinity of the release point.”

The Environment Agency says this means that the effects of the pollutant will have been ‘short lived’ and any effects on wildlife would have been ‘negligible’.

A statement added: “There would have been no danger to pets.

“The chemical has long since been diluted in the river, which will be back to normal now.”

The section of river affected by the pollution lies close to the Rivington Water Treatment Works, which is run by United Utilities.

The water company says it is co-operating fully with the Environment Agency’s investigation.

Local residents, who regularly chose to walk in the popular beauty spot have been shocked by the incident and are continuing to post images of the dead fish on social media.

And local people are demanding answers as to where the pollution came from and whether someone is to blame for the incident.

However, resident Bev Howell, in a Facebook post, called for patience, stating: “They won’t name until they have all the facts and nor should they.

“These things take time to investigate and testing samples for contaminates takes time much in the same way it takes time for our blood tests to come back from the hospital.

“Hopefully the EA will clear everything up quickly.”

The River Douglas is 56 kilometres in length and runs through Lancashire and Greater Manchester.

The source of the river is found at Winter Hill and the mouth is at the River Ribble, of which it is a tributary.

The fish were found in a section of water near to Squirrel Lane, which lies off Bolton Road.

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