UNITED Utilities and a group of construction companies have admitted illegally allowing bleach to get into a Bolton stream.

The Environment Agency took action after alarmed members of the public found hundreds of fish dead in Bradshaw Brook in December 2013.

The agency traced the pollution to the Wayoh water treatment works at Turton Bottoms, finding bleach, chemically known as sodium hypochlorite, had been released into the water course on around December 4 that year.

Sodium hypochlorite is widely used in households and industry, including being used for water purification.

At Bolton Crown Court, counsel for United Utilities Water Ltd pleaded guilty, on the company’s behalf, to causing a water discharge activity not under and to the extent authorised by an environmental permit contrary to regulation 12(1)(b) and 38(1)(a) of the Environmental Permitting (England & Wales) Regulations 2010.

KMI Plus, a joint venture made up of four companies working on infrastructure projects for United Utilities, also pleaded guilty to the same offence.

The regulations state that a person cannot cause or allow discharge into water without a permit authorising them to do so and contravening the rule is an offence.

At the time of the bleach release KMI Plus, a partnership of Kier Infrastructure and Overseas Ltd, J Murphy & Sons Ltd, Interserve Construction Ltd and Mouchel Ltd, were undertaking a £400 million programme of work for United Utilities to design, construct and commission several projects across Lancashire and Cumbria.

The works were designed to upgrade the water treatment and distribution infrastructure and help improve the environment.

But the alarm was raised in December 2013 when hundreds of fish were found dead in Bradshaw Brook near Jumbles Reservoir.

The Environment Agency set up an incident hotline and urged anyone who saw further fish in distress to call them.

At Bolton Crown Court the case against United Utilities and KMI Plus was adjourned until June 13 when a trial of issue will take place for a judge to establish the level of responsibility the companies have for the offence and the degree of harm caused.

Penalties for the most serious criminal offences committed in breach of the regulations carry unlimited fines and up to five years in prison.