Check if you need a licence to impound water
Source: gov.uk (2025-06-25)

If you impound water, or plan to, you may need to apply for an impounding licence.

An impoundment is a dam, weir or other structure within inland waters that can permanently or temporarily change the water level or flow.

You must have an impounding licence before you start to construct, alter or remove an impoundment structure, even in an emergency.

If you have an existing licence you may need to change it if you want to alter or remove the structure.

An impounding licence will set out:
- the manner and extent of the impoundment structure and any conditions related to its construction and operation
- any diversion works required which are associated with the construction
If you impound water without a licence when you need one the Environment Agency may take enforcement action.

There are some situations where you may not need an impounding licence.

Exemptions

You do not need an impounding licence if your activity is exempt.

The exemptions are for:
- works constructed without a licence before 1 April 2006, except when the Environment Agency gives notice that a licence is needed
- navigation, harbour or conservancy authorities that obstruct or impede the flow of water in waterways or harbours they manage in the course of their duties
- impounding works authorised by a drought order or drought permit
- structures and works authorised by legislation (for example an act of Parliament) – a licence may be required if you plan to alter or remove the structure
- works authorised by a development consent order, if the Environment Agency has agreed that an impounding licence is not needed
- when the Environment Agency gives notice requiring impoundment only for the purpose of screening or passage for eels
- works constructed after 1 April 2018 by or on behalf of an internal drainage board in the district they manage in the course of their duties
- works constructed after 1 April 2018 within a managed wetland system if the impounding works are for the sole purpose of managing the wetland system – managed wetland system is defined in regulation 2 Water Abstraction and Impounding (Exemptions) Regulations 2017 (https://www.legislation.gov.uk/uksi/2017/1044/regulation/2)
- works carried out in an emergency by or on behalf of navigation, harbour or conservancy authorities – a notification must be sent to the Environment Agency within 5 days of the work commencing; emergency is defined in regulation 10 Water Abstraction and Impounding (Exemptions) Regulations 2017 (https://www.legislation.gov.uk/uksi/2017/1044/regulation/10)
Low risk impounding activities

Some impounding activities that require an impounding licence have a low impact on the environment and other water users.

The Environment Agency will not normally take enforcement action if you do not have an impounding licence for these low risk activities if you meet the conditions in the Environment Agency’s regulatory position statement low risk impounding activities: RPS 302 (https://www.gov.uk/government/publications/low-risk-impounding-activities-rps-302).

The regulatory position does not apply to any other legal requirements.

Apply for a licence to impound water

Find out how to apply for a licence to impound water (https://www.gov.uk/guidance/water-management-apply-for-a-water-abstraction-or-impoundment-licence).

Other permissions you may need

You may also need to apply to the Environment Agency for an environmental permit for a flood risk activity (https://www.gov.uk/guidance/flood-risk-activities-environmental-permits) when you build in, over or next to main rivers. For rivers and watercourses that are not main rivers you must apply to your lead local flood authority for consent.

If you want to abstract (take) water, check if you need an licence to abstract water (https://www.gov.uk/guidance/check-if-you-need-a-licence-to-abstract-water).

Get advice

If you are not sure if your proposal needs an impounding licence, you can get advice using the Environment Agency’s enhanced pre-application service (https://www.gov.uk/guidance/get-advice-before-you-apply-for-a-water-abstraction-or-impounding-licence).