Nutrient Neutrality

In 2018, the Court of Justice of the European Union saw a landmark change in case law by, what is now referred to as, the ‘Dutch Case’. A combination of two reports in the Netherlands brought attention to the harmful level of nitrogen in water systems due to agricultural activity. This highlighted the need for an appropriate assessment to be taken prior to any new developments where it is expected to produce high levels of nitrogen or phosphorous which can end up in the water system.

Nutrient Neutrality describes the approach of avoiding a net increase in nitrogen and phosphorus in the water system through better land and wastewater management. The two most prominent sources for increased levels of these nutrients are fertiliser run off from agriculture and poor wastewater treatment works. When the nutrients reach a water system, eutrophication can occur whereby the increased in levels of nitrogen and phosphorus allow the accelerated growth of excess plant and algae in marine habitats. The most harmful consequences of eutrophication are algal bloom (algae production) and hypoxia (reduced oxygen levels in water) which damage the aquatic ecosystem, killing native fish and plant species and destroying important habitats.

Following the ‘Dutch Case’, Natural England outlined guidance for local councils whereby planning permission would only be granted if the plans proposed demonstrate adequate consideration for the level of excess nutrients produced. In 2020, they clarified their guidance stating that the amount of nitrogen entering the water system must be offset by removal of the equivalent amount of nitrogen from the effected water system. Developers are expected to use a Nitrogen Budget to audit the level of nitrogen prior to development and include a clear strategy for achieving neutrality within the proposal by offsetting the production of nutrients.

Offsetting the production of excess nutrients can be accomplished on the development site or off-site by taking certain land out of production. This can include the creation of greenspaces, such as rewilding or establishing trees; or removal of nutrients before it reaches the water system through wetland creation or better wastewater management. One creative example would be the establishment of reed-beds to filter out nitrogen before it reaches a local water way.

Whilst there is not yet a national regulation for Nutrient Neutrality, one emerging idea is to create a credit for capturing excess nitrogen which can then be traded to landowners unable to limit excess nutrients reaching the water system. This scheme is currently being trialled by Eastleigh Borough Council where they are facing a significant need for more housing at the cost of nitrogen pollution in the Solent. Eastleigh Borough Council use council owned land to capture excess nitrogen through effective land management practices; developers can then offset their nitrogen production by purchasing credits from the council thereby reducing nitrogen levels in the local water system.

Here is West Berkshire the Rive Lambourn has been announced as a Nutrient Neutrality Zone. We will let you know what BioCap thinks this means for us all when we have managed to unravel the guidance documentation!

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