Ashtead pleaded guilty to causing or knowingly permitting polluting matter to enter controlled waters, contrary to section 85(1) of the Water Resources Act 1991. It was fined £5,000 and ordered to pay costs of £3,724. The incident was discovered following a report from a member of the public that there was oil in the stream at Gatebeck, Cumbria. An investigation by the Environment Agency found that a generator serving a mobile phone transmitter had been stolen. The fuel lines had been left to drip on the ground and diesel had seeped into the soil and into the stream. The pollution was only metres away from United Utilities' underground Thirlmere aqueduct, which provides water for 250,000 households. Although the Agency recognised that a third party had been responsible for the generator theft, it argued that it was Ashtead's responsibility to ensure the machine was kept safely and securely. It was the second such incident at the site.