Activities that need a marine licence



When is a marine licence required?

A marine licence is required when any licensable activity as defined in section 66 of the Marine and Coastal Access Act 2009 is undertaken within the marine licensable area.

Which activities require a marine licence?

In broad terms, a marine licence is required if one or more of the activities are to be undertaken in the marine licensable area:

  • Any deposit or removal of material or substance, using a vehicle or vessel. Deposits or removals by hand are not marine licensable activities
  • Construction, alteration or improvement works (including works hanging/suspended over the marine licensable area and works beneath the sea bed eg tunnels, bridges and piers)
  • Scuttling vessels or floating containers
  • Dredging
  • Incineration of objects
  • Deposit and use of explosives
  • Harvesting or growing aquaculture (seaweed or shellfish)

Read more about low risk activities which require a licence.

Where is the marine licensable area?

The Welsh marine licensable area includes the Welsh inshore and Welsh offshore region. The Welsh inshore region extends seaward 12 nautical miles from Mean High Water Springs (MHWS) to the territorial limit. The Welsh offshore region extends beyond the territorial limit to include all areas of the sea in the Welsh Zone.

This area is defined in the Marine and Coastal Access Act (section 42) as any area submerged at mean high water spring tide, and the waters of every estuary, river or channel, so far as the tide flows at mean high water spring tide. The licensable area also includes waters in any area which is closed, whether permanently or intermittently, by a lock or other artificial means against the regular action of the tide, but into which seawater is caused or permitted to flow, whether continuously or from time to time, and from which seawater is caused or permitted to flow, whether continuously or from time to time.

How do we define Mean High Water Springs (MHWS)?

We do not define Mean High Water Springs, but ask applicants to provide evidence if the exact line is in question.

Lines on OS maps can be used as a general guide but are not used definitively as MHWS moves so dramatically over time, particularly following storm events.

One way to show MHWS is to use height data from the closest port and a ground level survey at the works site.

MHWS for primary ports are available (along with conversion from local datum to AOD (above ordnance datum)) on the National tidal predictions for UK and Irish Ports website.

There may be more local figures commercially available for MHWS around Wales which could provide a closer height. These are of course fine to use.

Which activities are exempt from the requirement for a Marine Licence?

Some activities may not require a Marine Licence and are defined as exempt.

These are set out in the Marine and Coastal Access Act 2009, Part 4, Chapter 2, for example, dredging and associated disposal authorised under local Acts or Harbour Orders – these need to be considered on a case by case basis.

Other activities that do not require a Marine Licence are identified in the Marine Licensing (Exempted Activities) Order 2011.

Read more in marine licence exempted activity.

Still not sure if you require a marine licence?

If you are still unclear whether your activity requires a marine licence and you need to come to us for further guidance, please provide the following information with your query:

Details of the works to be undertaken, including:

  • Whether the works are seaward of Mean High Water Springs and in Welsh Territorial Waters? Please provide a map
  • Will vehicles or vessels be used to undertake the works?
  • Size and scale of the work?
  • Time of year the works are to be undertaken?
  • Are the works within a designated site?
  • Have discussions been held with any other function of NRW previously? Who? When?
  • Description of the works, including method to be used

The marine licensing team can be contacted at the following email address:

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