Last edited 02 Feb 2022


According to the Environment Agency, a watercourse is ‘…any natural or artificial channel above or below ground through which water flows, such as a river, brook, beck, ditch, mill stream or culvert.’ Ref. Living on the Edge, Environment Agency 2014.

Watercourses can be open, or can be underground and may sometimes be dry. Very broadly, watercourses are defined as main rivers or ordinary watercourses:

Owners of land that is next to or includes a watercourse have riparian rights and responsibilities. There may be a number of parties with riparian rights and responsibilities along the length of a watercourse, particularly where it runs along a boundary between two properties. Where land is rented, the parties should agree who is responsible for the watercourse.

Riparian landowners are responsible for:

Risk management authorities have powers over and responsibilities for watercourse management. These include:

Works to ordinary watercourses other than cleaning and routine maintenance must be approved by the Lead Local Flood Authority. They may also require planning consent from the local authority, who will consult with the Environment Agency.

The Lead Local Flood Authority has powers to enforce riparian responsibilities and can serve notice on owners and carry out works themselves if watercourses become blocked resulting in a flood risk or a health hazard.

It may be necessary to obtain a licence from the Environment Agency to abstract water from or impound water on a watercourse.

Internal Drainage Boards (IDBs) are local public bodies established in areas of special drainage need to manage flood risk and water levels on behalf of their community.

NB The SuDS Manual (C753), published by CIRIA in 2015 defines a watercourse as: '... all rivers, streams, ditches, cuts, culverts, dykes, sluices and passages through which water flows.'

NB Culvert, screen and outfall manual, (CIRIA C786) published by CIRIA in 2019, defines a designated watercourse as: 'A watercourse in Northern Ireland on which the Department for Infrastructure (DfI) has powers to undertake, construct and maintain drainage works, to carry out emergency works and to make byelaws.'

Watercourses not designated as a main river are known as 'ordinary watercourses'.

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