Mersey Estuary Conservation Group
  • Home
    • Members and Observers
    • Publications
    • Links
    • Tide Times
  • The Importance of the Estuary
    • WORLD WETLANDS DAY
    • The Mersey Estuary
    • The Tidal Bore
    • Black-tailed Godwits on the Upper Mersey Estuary
    • Dunlins on the River Mersey
    • Canada Geese
    • Cetaceans, Dolphins and Porpoise.
    • Cormorants on the Upper Mersey Estuary
  • Mersey WeBS July - Dec 22
    • Mersey WeBS Dec 21 - Jun 22
    • Mersey WeBS = Jan - Jun '20
    • Mersey WeBS = Jul - Dec 2019
    • Mersey WeBS Jan - Jun 2019
    • Mersey WeBS = July - Dec 2018
    • Mersey WeBS = Jan - Jun 2018
    • Mersey WeBS Jul 20 - Nov 21
    • Does your birding count?
  • News Items
    • Mersey Tidal Power
    • Pink footed geese on the Mersey
    • The Mersey Estuary Needs Your Help
    • Biobitz at the River Park
    • Harbour Porpoise Spotted on River
    • MECG Visit To The Coffer Dams
    • Inshore Fisheries and Conservation Authority - Poster.
    • Tidal Power from Estuaries?
    • Mersey Narrows and North Wirral SPA
  • Locations
    • The North Shore >
      • Garston Coastal Reserve
      • Hale Conservation Area
      • The Oglet Project
      • Pickerings Pasture Local Nature Reserve
      • Butterfly Walks at Garston Coastal Reserve BioBlitz
      • Botanical walk along Hale Shore
    • The South Shore >
      • Mount Manisty
      • South Mersey Marshes
      • Woolston Eyes
      • Port Sunlight River Park
    • WeBS Counts on the River Mersey
  • The Peoples' Walk for Wildlife
  • Mersey Gateway Project

The Mersey Estuary

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Map of the Estuary.
The Mersey Estuary stretches for a distance of about 30 miles from the upper tidal limit of Howley Weir in Warrington to the sea. At its widest point, between Hale Head on the north shore and Ince Bank on the south, it is about five kilometres across. The estuary can be divided into four distinct zones:

The Upper estuary, between Warrington and Runcorn is narrow and consists largely of a single, meandering channel. At Runcorn the estuary is constricted through the “Runcorn Gap”, a narrow outlet between sandstone ridges running roughly north / south.

Below Runcorn the estuary opens out into a wide basin, the Inner estuary. This is characterised by the presence of extensive intertidal sand and mud flats with areas of salt marsh on both banks. Historically the positions of the low water channel and the shape and height of the banks in the Inner estuary have varied, migrating from one side of the estuary to the sandbanks.


Seaward of the Inner estuary the underlying geology has forced the channel into a long, straight section - The Narrows. This is subjected to strong tidal currents that prevent the accumulation of sediments and has resulted in a channel reaching depths of up to 20 metres.

Finally there is the Outer estuary which is bounded to the seaward end by a line between Formby Point to the north and Dove Point on the north Wirral coast, to the south. The Outer estuary consists of an extensive area of intertidal sandbanks. The Crosby and Queens Channels are maintained  through these by dredging between training banks.
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