Yesterday at around 3pm over 200,000 litres of industrial waste ran into a small brook that flows directly into the River Dee at Cefn Mawr, near Wrexham, north Wales, EA officers said.
A spokesman said there have already been uncorroborated reports of dead fish in the river but it was too soon to assess the extent of the damage.
The Environment Agency officer said: “We estimate more than 200,000 litres of diluted industrial effluent was released into a brook – a short length of river that goes into the Dee.
“It happened at Cefn Mawr, near Wrexham. We alerted the water companies immediately so they could take precautions. We took some samples yesterday and are waiting for the results.”
The source of the leak is from the Cefn Mawr Chemical company Flexsys who said they were working with the EA to establish the cause.
A company spokesman said: “At 2.50pm yesterday, a storage tank in our waste treatment plant began to leak dilute liquid into the River Dee via Trefnant Brook. Our immediate response was to suspend manufacturing operations and direct all available resources to protect the river.
“Staff at the site initiated our emergency plan for an environmental incident by calling the emergency services and the Environment Agency. Working in conjunction with the county emergency services, the leak from the tank was contained on site by 4.20pm. By early evening the emergency services were able to leave the site.
“This morning we will work with officers from the Environment Agency to conduct a full investigation to establish both the cause of the leak and to properly assess the environmental impact,” he added.
The River Dee which is one of the most closely monitored waterways in Europe. In July 2000 a pollution killed over a 100,000 fish and the source of the contamination was never discovered.
Last year some 150,000 fish, most of them salmon, bred at the EA hatchery at Maerdy, near Corwen, to restock the Dee, died from pollution.
