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.

The high input levels of nitrogen in the water causes eutrophication by turbo-charging algae growth, wreaking havoc on ecosystems and suffocating the life out of our seas. The blooms of green algae negatively impact the Solent area’s protected habitats and species, particularly where rivers meet the sea. Here the algal growths form dense green mats which frequently cover the Solent’s mudflats, stopping oxygen from reaching the animals in the sediment and killing off some of our most special habitats and species, including seagrass meadows, and nurseries for species such as sea horse, bass and cuttlefish.

The algae also form a barrier to birds such as the many waders and waterfowl that depend on the life in the mud for their food and rely on probing the mud or picking off tiny invertebrates from its surface.  These mats can also smother some of our most threatened habitats such as seagrass beds and salt marshes, choking them to death and risking erosion.

Natural England has approved a nitrate mitigation model that offsets nitrate arising from the built environment by removing intensively farmed land from agricultural production.  This land has historically been fertilised using nitrate-based fertilisers and grazed livestock – by ceasing this land management in perpetuity, a nitrate credit is created to offset the nitrates discharged into the environment by development.