The company has also agreed with the Environment Agency to put right any damage caused by the incident, in which 150 fish died when sewage water was pumped into Houghton Brook for a period of about 10 hours.According to the Environment Agency, the overflow was caused by excessive levels of un-flushable material blocking a pump, which was a known issue at the works, in Ilex Road. Other contributing factors included a second pump being out of service during the incident and the failure of an alarm. At the time of the pollution the water company took steps to prevent pollution travelling further downstream and two days later the stream was running clear. Anglian Water has since replaced equipment at the pumping station including a pump that, it says, can better cope with high levels of material. Following the incident, which occurred in September 2014, Anglian Water agreed an enforcement undertaking with the Environment Agency, with the latter accepting an offer to put right any damage caused by the pollution and to donate to an environmental charity. As part of the agreement, the water company has donated £100,000 to the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire to benefit the local environment and also paid the agencys costs. Jeremy Hay, Environment Agency officer, said: Enforcement undertakings allow those who commit offences to restore the environment and to take steps to prevent a recurrence. When appropriate, they allow a quicker resolution than a prosecution and help offenders who are prepared to take responsibility for their actions to put things right voluntarily working with their local communities. Formal sample results taken after the incident showed that sewage had polluted approximately 635m of the stream. The undertaking was offered in relation to an offence of pollution under section 4 of the Salmon and Freshwater Fisheries Act 1975. It was accepted in March 2017 and the undertaking was completed in May. An Anglian Water spokesman said: Ultimately our goal is no pollutions and we have a significant programme of activity and investment to help achieve this and understand the causes of any that do occur. We regret any that do happen, no matter how small, and support enforcement undertakings as a sensible, proportionate response that benefits local communities and the environment. Fortunately the environmental impact was limited and the environment was recovering the next day. Our donation to the Wildlife Trust will be used to further improve the local environment. We take our role protecting the environment extremely seriously but we also need customers to play their part. When our technicians attended our pump on Ilex Road they found it was blocked with wet wipes, nappies and sanitary products and therefore had stopped working. This is why we ask customers to think before they flush and only flush the three Ps (poo, pee and paper). Engineers worked through the night to get the pumps back to normal and complete a thorough clean-up.