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.

If a watercourse runs through or next to your land you are a 'riparian landowner' and you will have responsibility for managing the watercourse.

Formerly known as 'main rivers', watercourses are designated by the Department of Infrastructure and are of general significance for flood risk management (FRM).

We may provide, maintain, improve or extend designated watercourses or FRM works to protect the Island from flood risks.

We may provide, maintain, improve or extend non-designated watercourses or FRM works only if:

  • there are circumstances posing a serious flood risk
  • to mitigate the consequences of flooding



Floodhub Biosecurity Statement

The Flood Management Division understand that maintaining biosecurity – preventing the introduction and/or spread of disease or harmful organisms – is vital in preserving the Island’s environment. Whilst the Isle of Man has a ‘Disease Free Status’ with no current notifiable diseases, parasites or invasive macroinvertebrates, we check to ensure we don’t spread invasive plant species. The Flood Management Division follows the ‘Check, Clean, Dry’ approach  (see NNSS for more information).

The Island is continually vulnerable to new species arriving on our shores. These may arrive from a variety of sources including shipping, infected equipment use in freshwater, wildlife migrating to the island, and imports. Any equipment taken off-island is thoroughly cleaned and disinfected, with off-island contractors instructed to do the same before commencing work. Non-native fish species are present on the Island, with the importation and movement of these species restricted under the Coarse Fish Policy 2015. For more information, see the Aquatic Pets, Imports and Disease Control government website.