Achieving Nutrient Neutrality

Poor water quality is a major issue across England as nutrient pollution has a seriously detrimental impact on our habitats and the wildlife they support. As a result, any development proposals in high nutrient catchments with the potential to affect water quality, must demonstrate how they will achieve nutrient neutrality.

What is nutrient neutrality?

Following the Dutch Nitrogen case in 2018, Natural England has designated certain European Protected sites as being in unfavourable conservation status due to the nutrient loading in those sites. Any development which may increase those nutrient levels can't be permitted.

Natural England has proposed developers must show how their projects will achieve ‘nutrient neutrality’ before they get the green light to proceed. But what does this mean for your development and how do you move forward?

Construction projects of all sizes can create additional water pollution, mainly though wastewater. The current focus sits with housing, due to the impact of increased sewerage, but it can become a problem for other sectors such as the leisure industry and agriculture.

To achieve nutrient neutrality, and the subsequent planning approval, a project must add no additional water pollution and provide mitigation measures that will help tackle the current levels on that site. The implications of this are that many local authorities can't currently grant planning permission for projects without suitable plans in place and we estimate that 10’s of thousands of new proposed houses will be put on indefinite hold if a solution is not found.

Nutrient Management Plans

Local authorities and other interested parties are trying to address the issue through the development of Nutrient Management Plans for various catchments, but the progress is slow.

 Regions originally affected:

  • The area around the Solent
  • The River Avon catchment
  • Areas along the Stour catchment in Kent (Ashford and Canterbury)
  • Parts of Hertfordshire
  • Somerset Levels

However, recently Natural England have identified more areas to join this group, including:

  • Chesil and the Fleet SAC/SPA
  • Esthwaite Water Ramsar
  • Hornsea Mere SPA
  • Lindisfarne SPA/Ramsar
  • Oak Mere SAC
  • Peak District Dales SAC
  • River Axe SAC
  • River Clun SAC
  • River Derwent & Bassenthwaite Lake SAC (only applies to catchments of Bassenthwaite Lake (River Derwent and Tributaries SSSI unit 1) and River Marron (unit 124 of River Derwent and Tributaries SSSI).
  • River Eden SAC
  • River Itchen SAC (part of Solent Catchment)
  • River Kent SAC (only applies to catchments of units 104 and 111 of River Kent SSSI)
  • River Lambourn SAC

In short, this will be a challenge for many years to come.

The role of nature-based solutions

Nature-based solutions (NbS) work with nature to benefit both society and biodiversity. They protect, restore and manage ecosystems and can be used to sustainably manage agricultural land, forestry and our rivers and coastal waters. They also include urban interventions and masterplanning design to build in green spaces such as green roofs, pocket parks, rain gardens and planting more urban trees.

They provide a range of benefits, including enhanced biodiversity, flood alleviation, better livelihoods for local communities, and they contribute to greenhouse gas reductions, either by storing carbon or by preventing its release.

As governments commit to and prioritise the restoration of nature and biodiversity, a holistic, nature-based approach to development is rapidly becoming the key to success when it comes to moving development plans forward.

Typical nature-based solutions include:

Achieving Nutrient Neutrality

Our environmental and planning experts develop and implement designs for onsite and offsite nature-based solutions to tackle nutrient neutrality.

We can bring landowner and developer clients together to facilitate the design and construction of wetland features that will capture water-borne nutrients which already exist in local water courses and that originate from agricultural runoff and from urban areas that drain to the water courses.

This decrease in nutrients, by virtue of being located in the same catchment as the treated effluent from the new development, provides a local offsetting solution. And many are multi-functional. They can also provide carbon sequestration and deliver habitat credits for biodiversity net gain too. Flood storage and other natural capital benefits also arise if the design is carefully configured.

Our technical specialists assess the baseline conditions; and can model and measure the site performance and outcomes to validate credits and income. These assessments range from surveying and recording habitat enhancement to validating the nutrient cation exchange capacity and thus ability of the constructed wetland to store nutrients. 

The use of nature-based solutions to clean up rivers, extracting both phosphorous and nitrates to help to combat eutrophication ensures that new urban areas are nutrient neutral, allowing planning permissions to be secured.

Our portfolio approach

Our specialists can advise on all aspects of NbS with a focus on integrating nutrient, Biodiversity Net Gain, Environmental Land Management System and carbon capture solutions.

Our integrated, holistic solutions:

  • Provide nature-based benefits in priority areas identified for enhancement/ improvement
  • Deliver habitats that are nutrient and carbon sinks: peatlands, wet grassland; wetlands, fens and wet woodlands
  • Increase connectivity for biodiversity
  • Tackle ‘nutrient neutrality’ issues in sensitive river catchments
  • Deliver other multiple benefits – social, recreation, wellbeing, conservation, water management, flood protection.

 

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We believe that the full potential of peatland and wetlands have not yet been grasped.  We're working closely with developers to tailor new wetland into solutions for nutrient harvesting, water quality polishing, flood storage and even for wetlands to become carbon sinks. This approach to tailoring multiple benefits to a single location is critical for optimum performance whilst tackling water pollution and climate change.

Landowners and some project types such as onshore wind and solar are natural bedfellows for NbS because of the land around the infrastructure installed. This means renewables developers are now looking to maximise returns by building in significant NbS benefits on the land they manage.

Project spotlight

Constructed Wetland
River Avon, Hampshire

To help our client, Taylor Wimpey, tackle their nutrient neutrality challenge, we completed an outline design for a constructed wetland on the bank of the River Avon.

Our wetland solution uses natural processes to reduce the nutrient load in the river creating ‘headroom’ for new development within the catchment.

 

 

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Our assessments demonstrated that a large number of nutrient credits should be generated by adapting the design of the wetlands and reedbeds to remove phosphates (and also nitrates) from the river. These two functions can be designed to be compatible.

Through our multi-disciplinary teams, we've backed up our design with detailed modelling of the nutrient removal performance. The inclusion of high-quality habitats such as permanent ponds, wet grassland restoration and native hedgerow, also provide significant ecological enhancement that can be quantified and traded as new ‘habitat units’ through the emerging BNG process.

There is also an opportunity to ensure the design can allow the retrofit of additional flood storage at a later date to allow our client to capitalise on any natural capital benefits they may be rolled out in the future.

Get in touch

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Nick Betson

Technical Director T: +44 (0) 23 8081 0440 Email
Southampton | UK
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Mike Barker

Director of Ecology T: +44 (0)1480 466335 Email
Cambridge | UK
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Ola Holmstrom

Senior Director - Hydrology T: +44 1454 853 000 Email
Bristol | UK

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