MP Noah Law has said the pollution incident in the St Austell River is an “environmental disaster”.

The Labour MP for St Austell and Newquay was already highly critical of South West Water before the company confirmed that the source of the pollution was liquid lime which entered the river, also known as the White River, from its site in the Pentewan Valley, south of St Austell.

Mr Law had been pressing the water company to bring forward improvements to its “ageing” infrastructure and has described the pollution incident on Thursday, June 19, as potentially “a final straw”.

However, he said that he couldn’t comment further on the White River incident because it was subject to an ongoing investigation by the Environment Agency.

Meanwhile, the Environment Agency has detailed the steps it has taken since being alerted to the pollution incident.

Officers went to the White River on the Thursday to investigate after calls about dead fish. They identified a source of pollution and confirmed it had stopped by Thursday night.

A spokesperson said: “Many hundreds, potentially thousands, of fish were killed in the river including trout, eels and brook lamprey.

“Once the affected water travelled down the watercourse and was flushed out to sea, the pH of the White River stabilised and returned to normal neutral levels. On reaching the sea, the pollutant would have diluted and dispersed.

“Our officers returned to the site first thing on Friday morning and completed a thorough investigation. This included collecting a sample of the dead fish. This will be used as evidence for our regulatory action to bring those who pollute the environment to account.

“On the Saturday, our officers were on site monitoring the impact of the pollution on invertebrate communities in the river. This evidence is part of our continuing investigation.

“We take pollution very seriously and our officers are ensuring that South West Water are taking steps at the source of the pollution to prevent any reoccurrence.”

Cornwall councillor James Mustoe (Conservative), who represents the St Austell Bay and Mevagissey division, said: “There has been significant and extreme damage to the White River's eco-system, not just the fish that we all saw but the myriad of other lifeforms, invertebrates and smaller, that form part of the natural environment and have been wiped out here. We need a study as to what the damage was and steps need to be taken to restore the habitat sooner rather than later.

“If there is a fine as a result of any legal action, I want to see it invested straight back into the local area, to support things such as the valuable community work carried out by the White River Project Group to improve wildlife habitats and accessibility to the White River.

“I appreciate that legal cases can drag on for years, but I believe there’s no reason why we can’t get agreement on these matters sooner rather than later. I am grateful for Noah Law’s support on this issue, which quite simply transcends party politics.”