High levels of nitrates in the water of the Solent maritime area have caused the UK government, Natural England, and local planning authorities to develop nitrate neutrality policies so that new developments in the region have nitrate mitigation measures to offset their nitrates discharged via wastewater treatment works into the Solent.

Hampshire’s Warnford Park tree planting scheme is authorised by Fareham Borough Council and Gosport Borough Council, with S106 Agreements signed jointly with the South Downs National Park Authority. The Solent Nitrate Offset scheme is also advocated by the Winchester City Council, East Hampshire District Council and the Havant Borough Council for mitigating south coast planning applications dependent on the Solent’s wastewater drainage for new development schemes.