Main rivers

Our flood risk map shows the watercourses defined as main rivers in Wales

This includes any structure or appliance for controlling or regulating the flow of water in, into or out of a main river.
Main rivers are usually larger streams and rivers but also include some smaller watercourses. In Wales, main rivers are legally designated by Natural Resources Wales.

If you want to carry out works in, over, under or near a main river, or in a flood plain or flood defence (including a sea defence), you will need to apply for a Flood Risk Activity Permit (FRAP).

Find out how to apply for a FRAP for work on a main river 

Natural Resources Wales is responsible for maintenance and improvement work on main rivers in Wales to manage flood risk.

Every other open watercourse in Wales is known as an 'ordinary watercourse' and falls under the responsibility of your local authority (as the Lead local flood authority) or Internal Drainage District (Natural Resources Wales). 

Find out more

If you would like to understand more about main river designations, or discuss potential changes to the main river map, please contact us: