Conclusion 6

Abstracting too much water from rivers and other sources, including chalk streams, can damage the environment, and there are particular risks associated with HS2. Around 85% of the world’s chalk streams are in the UK and the aquifers (underground layers of rock that hold groundwater) that feed them are also used for the public water supply. The Environment Agency must balance the need to preserve the environment by maintaining flows with meeting the demand for water. On top of the threat of drying up caused by over-abstraction, chalk steams have also faced damage from sewage being discharged into them by water companies. The Environment Agency has prosecuted Thames Water on a number of occasions for breaching the conditions of its permits and allowing sewage to enter rivers from its treatment plants. Major infrastructure programmes also pose a threat. For example, in the Chilterns Area of Outstanding Natural Beauty, the HS2 programme needs up to 10 million litres per day to facilitate tunnelling. The Environment Agency says that it will not grant approval for HS2’s plans unless the project has both identified and then set out mitigation for impacts to groundwater sources. The Department told us that partnership grants to the value of £882,000 were provided to charities and stakeholder groups in 2020–21 specifically for the improvement of chalk streams and chalk habitat. The Department needs to consider whether this is enough to deal with what the Environment Agency described as a “clear and present danger”. Recommendation: The Environment Agency should write to us within three months setting out clear objectives, and its planned mitigation actions and associated timescales for eliminating environmental damage from over-abstraction and sewage outflow. 8 Water supply and demand management 1 The overall system for managing water resources