Written question asked by Lee Dillon (Liberal Democrat) on Tuesday, 10 June 2025, in the House of Commons. It was due for an answer on Thursday, 12 June 2025. It was answered by Lilian Greenwood (Labour) on Wednesday, 18 June 2025 on behalf of the Department for Transport.

M4: Newbury

Question: To ask the Secretary of State for Transport, if she will work with National Highways to ensure that runoff from the M4 does not pollute the chalk streams in Newbury.

Answer: National Highways (NH) is well aware of this issue, and in 2024 treated a site along the M4 that was found to be discharging into the River Lambourn chalk stream near Newbury. More generally, the Department is working closely with NH to address the risk of water pollution from the strategic road network and supports the prioritisation approach taken by NH in its efforts to mitigate pollution. This focuses on addressing verified high-risk outfalls as defined in NH’s 2030 water quality plan. The DfT and NH both recognise the importance of protecting chalk streams and NH is undertaking a review of its technical standard for road drainage and the water environment to give greater prominence to chalk streams.

Secondary information