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.
- Main rivers include rivers, larger streams and smaller watercourses of strategic drainage importance.
- Ordinary watercourse are rivers, streams, ditches, drains, sluices and so on which do not form part of a main river.
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:
- Accepting upstream water and transferring it freely to their downstream neighbour without obstruction, pollution or diversion affecting the rights of others.
- Maintaining the bed and banks of the watercourse and for clearing debris that could cause an obstruction on their land or by being washed downstream.
- Keeping structures such as culverts, weirs and gates clear of debris.
- Protecting the property from seepage through banks.
- Not using the watercourse for the disposal of any form of garden or other waste.
- Notifying the Environment Agency and the relevant risk management authority where works are planned to a structure that acts as an obstruction to a watercourse.
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.
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.'
 Related articles on Designing Buildings Wiki
- Base flow index.
- Catchment flood management plans.
- Coastal defences.
- Flood and Water Management Act.
- Flood insurance.
- Flood risk.
- Main river.
- River engineering.
- Thames barrier.
- The SUDS manual.
- Water Act 2014.
- Water engineering.
- Water framework directive.
- Water resources.
- Water table.