Main Rivers Consultation

Understanding the Main Rivers map and data

Go to the Main Rivers Consultation map


What are Main Rivers?

Main rivers are usually larger rivers and streams. Other rivers are called ‘ordinary watercourses’.

The Environment Agency carries out maintenance, improvement or construction work on Main Rivers to manage flood risk.

Environment Agency powers to carry out flood defence work apply to main rivers only. Lead local flood authorities, district councils and internal drainage boards carry out flood risk management work on ordinary watercourses


The Environment Agency decides which watercourses are main rivers. It consults with other risk management authorities and the public before making these decisions. The main river map is then updated to reflect these changes.


Key to understanding the Main Rivers Consultation map:

Main Rivers

The Main Rivers map shows which rivers in England are designated as Main Rivers.

  River Line - the blue line shows the main rivers, these are usually larger streams and rivers.

Main Rivers Consultation

The main rivers consultation map shows proposed changes to the designated Main Rivers.

  Additions - the green line shows the proposed new sections to the designated main rivers.

  Deletions - the red line shows the proposed removal of sections from the designated main rivers.


Go to the public consultation for all proposed Main Rivers changes


There are 2 reasons why the Environment Agency changes the main river map.

Designation changes

This is where the designation of the river changes to or from a main river. This means there is a change in who has legal power to carry out flood risk management work.

Factual changes

This is where the Environment Agency amends sections of the main river map to reflect changes in the environment or to correct inaccuracies. These changes only correct the line of the main river and do not change who has legal power to carry out flood risk management work.