Nutrient neutrality advice in the Lenham area

Planning applications or proposals

In July 2020, Natural England provided advice about water quality. This advice immediately affected planning applications for new homes in the parishes of Lenham and Boughton Malherbe. The Stour Valley river catchment area runs through Lenham, and part of the upper Great Stour river is within Maidstone Borough.

Natural England issued additional advice in November 2020. A full review of all the advice was published in March 2022.

Water quality advice

An assessment must be completed before new housing or development can be approved. It will assess if development could harm water quality in the River Stour catchment.

The assessment includes steps to reduce any harm to water quality at Stodmarsh. It checks the amount of nitrogen and phosphorus released by the development. This process is called 'nutrient neutrality'.

The Stodmarsh Nature Reserve is protected under European Law and is managed by Natural England. Natural England has identified that the water quality in the lakes has deteriorated. The water quality targets have also recently been tightened.

These documents may not meet accessibility guidance as they have been created by Natural England.

Previous Natural England advice

Ciria guidance

We also suggest reading the sustainable drainage systems (SuDS) relating to reducing phosphorus and nitrogen pollution. These documents were published by Ciria in 2022 and 2023.

The Stour operational catchment

The advice applies to the Stour Valley river catchment area. This area covers the eastern area of the borough, including most of Lenham and part of Boughton Malherbe Parishes.

It also applies to developments outside of the Stour Valley river catchment area, including those which would connect (directly or indirectly) to a Waste Water Treatment Works (WWTW) which discharges into the Stour Valley. This includes Lenham WWTW.

What you need to do

We are currently investigating possible solutions. A strategic solution is being developed in conjunction with Kent County Council and Natural England. This is expected to be published in Summer 2024.

Work on this was delayed between August 2023 and November 2023. This was due to prospective national legislation on the matter, which is no longer being proposed. This is further delayed due to waiting for government confirmation of successful funding.

However, we will be taking a precautionary approach and will require 'shadow' appropriate assessments for any planning applications, including those not yet determined.

If you have a planning application currently under consideration, you should:

read the advice from Natural England
speak with the planning case officer to discuss any suggested mitigation

If you wish to submit mitigation for phosphorus or nitrogen using SuDs strategies, you may need to pay us to have it independently assessed.

If you are thinking of submitting a planning application, you can:

ask Natural England for advice using their paid pre-application advice service
use our pre-planning application advice service