Flood Defences

Page updated on: 20/09/2019

Under the provisions of the Land Drainage Act 1991 as amended by the Flood and Water Management Act 2010 (FWMA), we now have a duty to control certain activities that might have an adverse impact on flood risk and the environment.

This means that you will need to apply for consent if you are planning on building a flood defence or carry out any work in an ordinary watercourse. We will then come out and check the proposed work methodologies to ensure that they will not negatively impact the environment through flooding, pollution, loss of habitats or damage to wildlife.

Below is a guide as to what activities require consent and which do not. Regardless of what you have planned, it is advisable to contact us prior to planning any works.


Works to the bank of a river does not require a permanent consent. However, depending on the flows and construction methodology, a temporary consent may be required.


If it is agreed with our engineers that the pipe does not obstruct the flow of the river, then consent is not required.


If the pipe does not interfere with flow, you do not require consent. However, the installation of the pipe may need consent. An open cut operation would require temporary consent while directional drilling would not.


This would not be permitted as it increases risk of blockage and flood risk. 


If a pipe is extending into the river from the river bank, you will require consent. 


If the pipe is set in from the bank with a concrete headwall and apron protecting the pipe, bed and banks from erosion, you may require temporary consent.  

We would rather that protruding pipes were designed with a concrete headwall and apron to ensure that the bank and bed are adequately protected. 


If the bridge does not obstruct flow then consent is not required. However, depending on the flows and construction methodology, a temporary consent may be required. 


Consent is required for all culverting works regardless of location, length or diameter.

Any proposed culvert should be equal or greater in size that the original channel thus affording equal or greater capacity.

All applications are subject to a hydrological check and if the required standards are not met then the application will be refused. We advise you to contact us first to agree the culvert size.


Grids and trash screens can perform a valuable role in keeping debris from culverts and preventing blockages. However, if not properly designed they actually cause blockages.

All screens will require consent. We recommend that you contact us first if you are thinking of constructing such a structure. 


Build up of gravel and shoal within a watercourse can increase the flood risk in an area. There are stringent environmental controls governing the removal of shoal and gravel from a watercourse.

You need to contact us to discuss any works of this nature. 

How to apply

There is an application fee of £50 per application and one structure is permitted per application. You will not be required to pay at this stage. Applications have a two calendar month determination period.

Apply for ordinary watercourse land drainage consent