HWTWRP - Biodiversity Net Gain - Market Engagement

The need for the HWTWRP Project is to create a new, resilient and sustainable water supply that will protect and enhance the county’s rare and sensitive chalk streams, while maintaining supplies for communities and the local economy. Biodiversity Net Gain (BNG) for the Project Biodiversity Net Gain (BNG) is an approach to development that aims to leave biodiversity in a measurably better state than beforehand. At the point of the Project’s submission, BNG was not a requirement for Nationally Significant Infrastructure Projects (NSIP) and therefore was not a legal requirement for the Project, despite this, the project has committed to the delivery of a 10% net gain. Mandatory BNG for NSIP applications came into force on 2nd November 2026 and applied to NSIP’s submitted from November 2026 onwards. The National Policy Statement for Water Resources Infrastructure (NPSWRI) states that “Development should contribute to and enhance the natural environment by providing net gains for biodiversity”. As such Southern Water has committed to delivering at least 10% BNG for the Project and has prepared a Biodiversity Gain Plan setting out its approach to the delivery of BNG. Following the application of the mitigation hierarchy, including the retention, reinstatement, creation and enhancement of habitats within the Order Limits, additional off-site biodiversity units will be required to achieve the Project commitment of at least 10% BNG. Where practicable, BNG will be delivered within the Order Limits as defined in the Development Consent Order (DCO) Application. However, a significant proportion of the required biodiversity units will need to be secured off-site. As far as practicable, all biodiversity units will be delivered within Hampshire. The current off-site BNG requirement is 201.77 biodiversity units, comprising: • 169.94 area habitat units • 29.69 hedgerow units • 2.14 watercourse units The indicative off-site habitats required to deliver these units are: • Other neutra