United Utilities fined after fish deaths in Bolton brook
More than 16,000 fish killed after unpermitted release
Last updated 9th Apr 2026
United Utilities has been fined £60,000 after more than 16,000 fish died in Bessy Brook near Bolton, Greater Manchester, following an unpermitted release during reservoir testing.
The water company pleaded guilty after introducing tens of thousands of fish into the small stream without a permit, in what the Environment Agency has described as a serious breach of environmental law.
Thousands of fish released during valve test
The incident happened on 12th December 2024 during a scour valve test at High Rid Reservoir in Horwich. More than 30,000 fish were discharged into Bessy Brook, an environment deemed too small and unsuitable to sustain them.
While United Utilities brought in contractors to rescue the fish, only around 8,000 were saved and returned to the reservoir.
The court heard the high-speed discharge caused devastating injuries, with some fish found embedded in bridge walls around two feet above the water. Others showed signs of severe trauma, including missing scales and protruding organs.
Investigation finds no pollution but serious harm
Environment Agency officers attended the scene on 13th December 2024 after reports of dead fish. Tests confirmed there were no pollutants in the water, with the deaths attributed to the physical impact of the release.
United Utilities suggested a large school of roach may have entered the pipework while trying to escape predators such as birds.
However, regulators concluded the release of around 34,000 fish caused “Category 2” harm, meaning a significant adverse impact on animal health.
First prosecution of its kind
United Utilities Water Limited was fined £60,000, along with a £2,000 victim surcharge and £24,098.06 in costs.
The case marks the first time a water company has been sentenced under The Keeping and Introduction of Fish (England and River Esk Catchment Area) Regulations 2015.
Environment Agency issues warning
Andy Brown, Water Industry Regulation Manager for the North West at the Environment Agency, said: “With this regulatory first, we are letting water companies know they must abide by all legislative requirements.
“The Environment Agency expects full compliance from water companies and are committed to taking robust enforcement action when we see breaches like this.
“United Utilities Water Limited has now paid the price for failing to obtain all relevant permits, while our hard-working officers will continue to do all they can to prevent future harm to the environment.”
Government response
Water Minister Emma Hardy described the incident as unacceptable and stressed the need for accountability.
She said: “This incident by United Utilities is shocking and should never have happened in the first place. The company has to be held responsible for its actions and this £60,000 fine does exactly that.
“Our reforms will create a new stronger regulator for the industry, with powers to do MOT-style checks on water assets, preventing failures like these from happening.”
United Utilities statement
A United Utilities spokesperson said: “We are sorry that this incident occurred and for the impact it had. We fully supported the Environment Agency throughout their investigation. Regrettably, the fish were harmed when they were released through a valve during a routine statutory safety inspection at the reservoir.
“We will ensure that lessons are learned from this incident and we have made a £500,000 donation to support a project to improve water quality in the nearby Middle Brook catchment.”