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The case for nutrient negativity

Ali Morse, Water Policy Manager at The Wildlife Trusts and Chair of Blueprint for Water, sets out the case for nutrient negativity.

This week, Blueprint for Water will be exploring levelling-up opportunities within the water environment - and how these could be secured through amendments to the Levelling Up and Regeneration Bill - in a series of blogs. Find these on our website here.

August 2022

Nutrients are a positive force; they nurture life, allowing arable crops, home-grown veggies and even our own bodies to grow healthy and strong. Yet in excess, they are problematic.

High concentrations of nitrates and phosphates (nutrients used in fertilisers, and found in slurry and in wastewater from our homes) cause havoc for our rivers, lakes and coastal waters. These plant nutrients super-charge the growth of algae. In rivers and lakes, ‘pea-green soups’ of abundant algae outcompete aquatic plants, and at the coast, dense algal mats and ‘red tides’ of algae, so numerous that they discolour the seas, leave mudflats and seaweeds smothered. The blooms may release toxins into the water, and even in death the algae continue their destruction, using up oxygen as they decay and suffocating aquatic wildlife.

This process, termed ‘eutrophication’, may sound like something from a horror film. But sadly, this scene is playing out all too commonly. At the last assessment, over half of England’s rivers and lakes failed standards for phosphate, whilst over two thirds of estuarine and coastal waters failed for nitrates. To tackle this pollution, there needs to be action on a range of fronts.

That which has hit the headlines is housebuilding: where protected wildlife sites are in poor condition because of nutrient pollution, development will only be permitted to proceed if it doesn’t add to that burden. Seventy-plus Local Authorities are now subject to the advice that such development should only be consented where it can achieve “nutrient neutrality”. This approach offsets nutrient inputs from development by reducing inputs from other sources such as agriculture, so that there is no adverse impact overall.

But is it enough just to ‘not allow things to get worse’? Nature is in freefall, with freshwater biodiversity declining more rapidly than that of either terrestrial or marine environments. In England, only 14% of waters are considered to be anywhere close to their natural state, and not a single one meets standards for chemical pollution. The foremost conclusion from the Environmental Audit Committee’s inquiry into water pollution, was that improving river water quality in England will be critical to meeting the target, established in law, to halt nature’s decline by 2030.

Government’s latest announcement on nutrient pollution does move us in the right direction, requiring upgrades to wastewater treatment works that discharge into the catchments of protected sites. But these will take many years to plan, finance and deliver. In the meantime, funding from Defra and DLUHC will unlock development by enabling Natural England to establish a ‘nutrient mitigation scheme’ – this will fund projects that reduce nutrient pollution and enable developers to purchase ‘nutrient credits’ to discharge their obligation to achieve neutrality.

Wildlife Trusts and other conservation organisations may be invited to take part in this scheme, as deliverers of projects that could provide this nutrient offsetting. But would we wish to? Nutrient offsets in and of themselves do nothing to help our rivers recover. This scheme could do much more. What if, project deliverers like ourselves insisted on holding back some of the credits that were generated? Whilst some would be used to allow Local Authorities to approve sustainable development in their areas, a portion would be held back, meaning that each development consented would effectively contribute to the slow but steady reduction of nutrient pollution afflicting our waters. On top of this, what we then do on the land providing those offsets would bring even greater benefits to people and nature – restoring or recreating habitats, and providing green and blue spaces for local communities.

Whilst conservation organisations would choose to take such an approach, other providers may not. There is, currently, no requirement to go above and beyond nutrient neutrality. But there could be.

An amendment to the Levelling Up & Regeneration Bill could require Nutrient Negativity as a condition of planning permission. What if, every development consented by a Local Authority, in an area where waters are eutrophic, secured a reduction in pollution? Biodiversity Net Gain has set such a precedent when it comes to nature, and the parlous state of our waters means that there is a strong case here too. A requirement for a fifteen percent reduction in pollution relative to pre-development levels would see progressive recovery in river health. Alongside newly-required investment in wastewater treatment, and the reductions in agricultural pollution that regulation and an ambitious Environment Land Management Scheme should bring, we may just be able to secure the kind of water environment that wildlife deserves, communities want, and society needs.

Ali Morse is Water Policy Manager at The Wildlife Trusts, and Chair of Blueprint for Water. 

Follow: @WildlifeTrusts & @this_damselfly

The opinions expressed in this blog are the authors' and not necessarily those of the wider Link membership.