Marine Conservation Zones and Planning in England

 

A Marine Conservation Zone, usually shortened to MCZ, is a statutory marine protected area designated under the Marine and Coastal Access Act 2009. MCZs protect nationally important marine wildlife, habitats and geological or geomorphological features.

There are currently 91 MCZs in waters around England. They range from estuaries and near-shore waters to offshore sites, so the issue is not confined to projects which look obviously “marine”. Coastal development, sea defences, ports, cables, pipelines, dredging and other works can all potentially affect an MCZ.

For planning purposes, the important point is that an MCZ has its own statutory conservation objectives and decision-making duties. It should not simply be treated as if it were a marine SSSI or a habitats site.

 

What does a Marine Conservation Zone protect?

 

Each MCZ has a designation order identifying the protected features and conservation objectives. The protected interest might include particular habitats, species, geology, geomorphology or the ecological processes on which those features depend.

The label “MCZ” therefore does not tell you by itself what a development must avoid. The first practical job is to obtain the conservation advice for the particular zone and understand which feature could be affected.

This matters because two developments at a similar distance from two different MCZs may have very different effects. The assessment follows the protected features and the impact pathway rather than a universal buffer distance.

 

MCZs are nationally protected sites

 

Natural England’s standing planning guidance lists Marine Conservation Zones alongside SSSIs as nationally protected sites. Local planning authorities must consider whether a proposal is on, near or otherwise capable of affecting an MCZ.

Natural England should be consulted where a planning proposal is likely to significantly affect the conservation objectives of an MCZ. For inshore and offshore marine work, other statutory bodies and the Marine Management Organisation may also have a role depending on the location and consent being sought.

A development can also affect several designations at once. An MCZ may overlap or sit close to a Special Area of Conservation, Special Protection Area, Ramsar site, SSSI or Heritage Coast. The relevant tests must be considered separately rather than assuming one assessment deals with everything.

 

What are the section 125 duties?

 

Section 125 of the Marine and Coastal Access Act 2009 applies to a public authority exercising a function capable of affecting, other than insignificantly, an MCZ’s protected features or relevant ecological or geomorphological processes.

So far as is consistent with the proper exercise of its functions, the authority must exercise those functions in the way it considers best furthers the MCZ’s conservation objectives. Where that is not possible, it must act in the way it considers least hinders those objectives.

Where the authority considers that its function would or might significantly hinder achievement of the conservation objectives, notification duties to the appropriate statutory nature conservation body can arise.

 

What is an MCZ assessment under section 126?

 

Section 126 deals with decisions to authorise activities capable of affecting an MCZ. Importantly, the explanatory notes to the 2009 Act make clear that this can include planning permission granted by a local planning authority, as well as marine licences and other consents.

In broad terms, the authority needs to consider whether there is a significant risk that the activity will hinder achievement of the MCZ’s conservation objectives. If that risk cannot be excluded, the Act contains further statutory tests before authorisation can be granted.

Those tests are not the same as a Habitats Regulations Assessment. A habitats site may require HRA and an overlapping MCZ may require a separate MCZ assessment.

 

Can development still be permitted if an MCZ is affected?

 

Potential harm does not create an absolute ban, but the statutory route is demanding. Where there is a significant risk of hindering the conservation objectives, section 126 provides a derogation route which includes consideration of whether there is another means of proceeding which would create a substantially lower risk, whether the public benefit outweighs the risk of environmental damage, and measures of equivalent environmental benefit.

This means an applicant should not jump straight to compensation. Avoidance and lower-risk alternatives can be central to the legal test.

For nationally significant energy infrastructure, the relevant National Policy Statements contain additional policy on MCZ assessment, but the statutory Marine and Coastal Access Act framework remains important.

 

Planning permission and a marine licence are different

 

Some coastal projects need planning permission for land-based elements and a marine licence for works below or around the marine area. Larger infrastructure may instead use a Development Consent Order with deemed marine licensing provisions.

Obtaining one consent does not automatically make the MCZ issue disappear from another regime. The project team should identify all required consents early and make sure the ecological and marine evidence is consistent across them.

Marine plans and the UK Marine Policy Statement can also be relevant to decision-making alongside terrestrial planning policy.

 

What impacts can affect an MCZ?

 

The answer depends on the protected feature, but common pathways can include:

• direct loss or damage to seabed habitat
• dredging, disposal and sediment movement
• changes to coastal or geomorphological processes
• turbidity and smothering
• changes to water quality
• underwater noise and vibration
• disturbance to protected species
• cables, pipelines, foundations and anchoring
• sea-defence or harbour works which alter physical processes
• construction pollution or accidental releases

The absence of a building inside the mapped MCZ therefore does not prove that there is no effect.

 

The Nature Restoration Fund and MCZs

 

The Planning and Infrastructure Act 2025 creates a new Environmental Delivery Plan and Nature Restoration Fund route which can, where an approved EDP specifically covers an MCZ protected feature and the relevant development impact, alter how that impact is treated under sections 125 and 126.

This is not a general exemption for development affecting MCZs. The new route only applies where an applicable EDP is actually in force and its requirements are met. The Government’s implementation programme has been bringing the first EDPs forward during 2026, so applicants should check the current position for the particular development and feature rather than assume the levy route is available.

 

What should an applicant check?

 

• use the current marine designation mapping to identify nearby MCZs
• obtain the designation order and conservation objectives for each relevant MCZ
• identify the protected feature and the realistic impact pathway
• check for overlapping SAC, SPA, Ramsar, SSSI and other marine designations
• identify whether planning permission, a marine licence or another consent is required
• engage the relevant statutory nature conservation body early where significant effects are possible
• consider lower-risk alternatives and avoidance before relying on mitigation or compensation
• check whether an approved Environmental Delivery Plan is relevant to the particular impact

 

Official guidance and maps

 

DEFRA – Marine Conservation Zone designations in England

Natural England – Protected sites and planning applications

Marine and Coastal Access Act 2009 – MCZ provisions

DEFRA – Implementing the Nature Restoration Fund

Conservation, Heritage & Protected Sites

 

Marine Conservation Zone Page Created: 27th August 2026