AN urgent investigation is under way after hundreds of fish were killed in the River Colne.
Dead fish have been spotted along a four-mile stretch of the river from Slaithwaite to Aspley over the past 48 hours.
And now experts are trying to pinpoint the source of the apparent poisoning.
The Environment Agency is asking for the public’s help in tracking down the source of the problem.
Reports of some smaller fish dying started to come in last Friday, and agency staff investigated that day but could find no apparent cause for the fish deaths.
More reports came in on Saturday and initial investigations showed that the problem could have been a discharge into the river from a blocked sewer.
However, the deaths started to appear upstream of that discharge. By Monday it was estimated that several-hundred stone loach had died, along with dozens of trout and some grayling, over a four-mile stretch of the River Colne between Slaithwaite and the Aspley canal basin near the town centre.
Environment officer Dave Preston has been following the case and said: “At first it was only the smaller fish that were hit but, as time has passed, the larger fish are now also becoming sick and dying.
“This suggests it’s a slow-acting pollutant that has somehow got into the water. If anyone has any evidence or information we’d welcome more information.
“The latest estimate is that several hundred fish are dead, and we’re still counting.
“Logic suggests that the pollution must have entered the river somewhere near Slaithwaite as the fish deaths start there, but we have been unable to trace the source.
“It may have stopped now, but we’d welcome any leads that anyone may have.”
The Environment Agency is treating the deaths as a Category One incident, the most serious level for this kind of river pollution.
John Beaumont, of Milnsbridge, regularly feeds fish in the village centre.
He said: “I spotted dozens of them, laid on the river bottom.
“The river looks normal but there are many, many dead fish. Whatever has gone into that river has wiped them out.”
Anyone with information is asked to call the Environment Agency Hotline on 0800 807060 or email firstname.lastname@example.org