Statutory guidance

Designation of ‘main rivers’: guidance to the Environment Agency

Published 16 November 2017

This guidance sets out the basis on which the Environment Agency should decide whether or not a river or watercourse is treated as a ‘main river’. The guidance has been issued under section 193E of the Water Resources Act 1991.

Main rivers are usually larger rivers and streams. They are designated as such, and shown on the Main River Map. The Environment Agency carries out maintenance, improvement or construction work on main rivers to manage flood risk. Other rivers are called ‘ordinary watercourses’. Lead local flood authorities, district councils and internal drainage boards carry out flood risk management work on ordinary watercourses.

The Environment Agency is responsible for maintaining a map of the main river (the Main River Map) and making any changes to it, and determining whether or not a watercourse, or part of a watercourse, is to be treated as a main river or part of a main river. This guidance has been issued by the Secretary of State for Environment, Food and Rural Affairs and the Environment Agency is required to have regard to it.

Criteria for determining whether or not a watercourse or part of a watercourse is suitable to become or to remain a main river or a part of a main river

References to a watercourse include both a whole watercourse and parts of a watercourse.

The criteria below are primarily directed at the management of flood risk. Any determination will need to be made in the context of the Environment Agency’s other relevant functions (and this may include environmental considerations, where relevant).

1. Principal criteria

Flood consequence

1.1. A watercourse should be a main river if significant numbers of people and/or properties are liable to flood. This also includes areas where there are vulnerable groups and areas where flooding can occur with limited time for warnings.

Managing flooding across the catchment

1.2. A watercourse should be a main river where it could contribute to extensive flooding across a catchment.

1.3. A watercourse should be a main river if it is required to reduce flood risk elsewhere or provide capacity for water flowing from, for example, a reservoir, sewage treatment works or another river.

2. Secondary considerations if changing the status of a watercourse

An efficient network

2.1. When considering changing the status of a watercourse, the Environment Agency should avoid short stretches of watercourses of alternating main river and ordinary watercourse status to provide clarity and to minimise inefficiency through multiple authorities acting on the same watercourse.

Competence, capability and resources

2.2. When considering changing the status of a watercourse, the Environment Agency should consider if those taking on responsibility have sufficient competence, capability and/or resources for flood risk management, including whether their governance enables sufficient competence, capability and/or resources, and local accountability. In carrying out this assessment, the Environment Agency should seek Defra’s views.

Other relevant criteria

2.3. The Environment Agency may have regard to other relevant factors that it considers appropriate when exercising its discretion to determine whether to change the status of a watercourse or part of a watercourse. The Environment Agency should consider relevant benefits or costs for the local community and representations from the local community and others in response to consultation.

Guidance in respect of consultation and publication under section 193C(2) and (5) Water Resources Act 1991

How proposed amendments are publicised

There are 2 types of change the Environment Agency may make to the main river map:

  • factual changes (updating the map so the location of watercourses is more accurate)
  • designation changes (changing an ordinary watercourse so that it is a main river, or a main river so that it is an ordinary watercourse)

Under section 193C(2) of the Water Resources Act 1991 the Environment Agency must publicise any proposed changes to the main river map and consider representations made.

1. Factual changes

1.1. The Environment Agency must publish notices of proposed factual changes on GOV.UK.

1.2. The Environment Agency should also consider contacting the landowners when the map is being amended to show the correct course of a culvert (a structure that lets the watercourse go under a road, for example).

2. Designation changes

2.1. The Environment Agency must publicise proposed designation changes by:

  • writing to any person who owns land next to the watercourse, and other key stakeholders (for example, Internal Drainage Boards or Local Authorities)
  • placing public notices in local newspapers
  • publishing notices on GOV.UK
  • placing notices in local buildings (for example, in libraries or council offices)

2.2. The Environment Agency should carry out proportionate and meaningful consultation on designation changes by:

  • giving stakeholders an opportunity to shape, comment on and influence the outcome - stakeholders include directly affected landowners, relevant public bodies, relevant interest groups and other persons, including the local community, affected by or interested in a proposed determination to change the designation of a watercourse
  • providing sufficient information and allowing enough time to enable stakeholders to understand how the proposal affects them and engage with the issues - this should include providing relevant information on the flood risk, environmental aspects, the costs and benefits for local communities and coordinating with those taking on the responsibility for the watercourse to help the public have access to information on proposed future management of the watercourse
  • taking into account the views of all those who respond to the consultation when reaching its decision.

2.3. Anyone aggrieved by the designation change has the right to appeal to the Secretary of State.