The Solent Mitigation Partnership is delivering a nutrient mitigation scheme through the upgrade of a council-owned sewage treatment works (STW) in Basingstoke.
Located within Basingstoke and Deane Borough Council’s administrative area and the Test and Itchen Nutrient Catchment, the STW previously discharged nutrients into the local water environment downstream. These nutrients, nitrogen and phosphorus, ultimately flowed into the Solent, affecting water quality and sensitive habitats.
The upgraded STW will operate with improved treatment processes that significantly reduces nutrient output. This reduction has been assessed and verified by Natural England, resulting in the generation of 77.79 nitrogen credits and 7.88 phosphorus credits. These credits are available to help offset the applications requiring both nitrogen and phosphorus mitigation in the eligible catchment.
Phosphorus mitigation from this scheme can cover housing developments and overnight accommodation in the Candover Brook sub-catchment. The map on the right shows that sub-catchment area of Basingstoke which is the northern most part of the River Itchen catchment and also includes elements of Winchester along the river.
Nitrogen mitigation from this scheme can cover housing developments and overnight accommodation in all the local authorities listed below that have planning authority in the combined Test and Itchen catchment – shown on the map.
To purchase or reserve credits from this scheme, the development must satisfy both of the following conditions.
A river catchment refers to the area of land where rainwater flows into a specific river or stream; it includes the river itself and all smaller streams and tributaries that feed into it.
Nitrogen: Developments must be located in the Test and Itchen Nutrient Rivers Catchment.
Phosphorus: Developments must be located in the River Itchen Nutrient Catchment
Only developments located in Basingstoke and Deane Borough Council’s administrative area are eligible for this scheme.
A former farmland site in Stubbington is now a nature recovery area, reducing nutrient runoff into the Solent. The project has generated over 400 verified nutrient credits to support sustainable development in the region.
The Solent Mitigation Partnership is working across Hampshire to deliver wastewater treatment works upgrades, enabling sustainable development.
A new scheme in Winchester will reduce nutrient pollution in the River Itchen by upgrading council-owned septic tanks. This will generate verified nutrient credits, helping unlock housing development while protecting the area’s sensitive ecosystems.
