Blackwater, Crouch, Roach and Colne Estuaries MCZ

Status: Designated


Site overview

This site is located on the Essex coast and includes the area where the estuary mouth joins the North Sea. This is one of the largest inshore Marine Conservation Zones (MCZ), a type of Marine Protected Area, covering an area of 284 km2.

This site is made up of saltmarshes and mudflats and is home to the native oyster. Sea snails, crabs and sea urchins live amongst the oyster beds. 

MPA Type

Marine Conservation Zone

Marine Conservation Zones (MCZs) are designated under UK legislation (Marine and Coastal Access Act 2009) and have been established around England, Wales and Northern Ireland to contribute to the UK MPA network protect a range of nationally important marine wildlife, habitats, geology and geomorphology, and can be designated anywhere in English and Welsh territorial and UK offshore waters.

Surface Area

284.40 km2 (109.81 mi.2)


1,366.36 km (849.01 mi.)

Coordinates (central point)

51° 42' 58" North, 0° 58' 39" East

  • Intertidal mixed sediments

    Sheltered shores where there is a mixture of pebbles, gravels, sands and mud and there may also be rocks and a few large boulders. Because it’s diverse, it provides a home for a wide variety of animals.

  • Maerl beds

    Maerl beds include several species of red seaweed, with hard, chalky skeletons. Maerl is rock hard and grows, unattached to the seabed, in little nodules or branched shapes on the seabed. Each bit is quite small, but they can accumulate in large areas tha

  • Native oyster beds (Ostrea edulis)

    Native oysters are two shelled animals - one half is like a cup and attaches to the rock, the other is flat and forms a lid. In shallow water on fine, muddy sand, they can be found in huge numbers and form extensive beds, which become home to many other m

  • Clacton Cliffs and Foreshore

    Clacton is one of the principal prehistoric sites in Europe and a site of considerable international importance. The sediment filled channels in this area reflect the ancient landscape and hold a diverse fossil record.

Seasearch Logo

Seasearch dives in 2012 recorded invasive slipper limpets as well as large areas of peacock fan worms at this site. Subsequently the rare sponge Suberites massa has been recorded here.

Learn more about Seasearch

Did you know?…

Over 170 parliamentarians from across the political spectrum signed up to our Marine Charter calling for a network of ‘marine protected areas’ in UK Seas

Over half a million people have voiced their support for ‘marine protected area’ designation in the UK through our campaigns