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Stodmarsh Nutrient Neutrality Guidance

Stodmarsh lies east of Canterbury and is a Special Protection Area (SPA), Ramsar site, Special area of Conservation (SAC), and a Site of Special Scientific Interest (SSSI) and parts are a National Nature Reserve (NNR). It is a site of national and international importance for a range of water dependent habitats and wildlife that relies upon them.

During 2017/18, a review of the internationally designated lakes at Stodmarsh identified that some of the lakes there had raised nitrogen and phosphate levels, leading to eutrophication of the lakes which occurs when an excessive amount of nutrients within a water body are present, resulting in increased plant growth that reduces the oxygen content in the water. This process makes it difficult for aquatic insects, invertebrates or fish to survive, in turn removing a food source from the food cycle.

In July 2020, Natural England (NE) issued advice to the Council on this matter in light of the relevant European case law.  This advice was updated by Natural England in November 2020 and recently again in March 2022. The advice and associated documents can be viewed from the links below.

For Dover District the advice covers the north-western parts of the District which are within the Little Stour and Wingham catchment area and/or development served by Dambridge Waste Water Treatment Works

Natural England Advice 2022:

NE Water Quality and Nutrient Neutrality Advice 16.03.2022

NN Stodmarsh Catchment Map

Nutrient Budget Calculator Guidance Stodmarsh

Stodmarsh SAC Nutrient Budget Calculator (excel)

NN Principles

NN – a summary guide

Natural England Advice 2020:

NE letter to authorities in Stour Valley Catchment

Stodmarsh NN methodology Nov 2020

Stodmarsh Non-Technical summary

Stodmarsh FAQs

DEFRA has published a policy paper in relation to the issue:

https://www.gov.uk/government/publications/nutrient-pollution-reducing-the-impact-on-protected-sites/nutrient-pollution-reducing-the-impact-on-protected-sites#our-protected-sites-and-nutrient-pollution

Dover Hydrological Modelling

DDC has questioned whether the advice is relevant for Dover District, given that the catchment is downstream of Stodmarsh. The Council commissioned hydrological experts to consider this issue.

Two reports have been produced which summarise the outputs of this work.

Impact of Dambridge WwTW on nutrient load in Stodmarsh SSSI – initial scoping study (December 2020)

Stodmarsh Water Quality Modelling November 2021

Discussions continue with Natural England on the outcomes of this work and the impact upon the nutrient neutrality advice for Dover District.

Until these discussions are concluded the position remains that Natural England consider that new development within the relevant part of Dover District will likely have an impact on nutrient levels within the protected sites at Stodmarsh and as such should be subject to their Nutrient Neutrality Advice.   

Strategic approach to Mitigation

The Council is working with the other local authorities in the Stodmarsh catchment to consider and implement mitigation strategies in the event that it cannot be concluded, through the discussions with NE, that development in Dover District does not impact upon Stodmarsh.

Determining Planning Applications

For current planning application for residential development or other overnight accommodation, proposals must demonstrate nutrient neutrality through the Habitats Regulations Assessment Process. The most recent Natural England guidance should be followed for applicants wishing to demonstrate this, and the information provided with the planning application. It is acknowledged that for most development proposals it will not be possible for this to be demonstrated without a strategic approach to mitigation which can be relied upon.

The advice is therefore resulting in delays to the determination of planning application within the affected area. In view of these continued delays, a decision has been taken, in respect of planning applications that were due to be reported to planning committee but were held up because of the nutrient issue, to now progress these through the planning committee process. Importantly, a decision of the planning committee to approve any such application would need to be subject to it being demonstrated that the development wouldn’t affect the integrity of the Stodmarsh Lakes designations or alternatively that satisfactory mitigation could be achieved. A planning approval couldn’t be released therefore (inter alia) until such time as this ‘subject to’ was satisfied.

 This approach has the benefit of ensuring the committee can consider all other aspects of an application, while the discussions/considerations with Natural England continue. This should hopefully reduce delays later and provide applicants with clarity about how the authority views their proposal.