Manchester Ship Canal - Ecology

Ecology

The quality of water in the ship canal remains adversely affected by several factors. The high population density of the Mersey Basin has, historically, placed heavy demands on sewage treatment and disposal. Industrial and agricultural discharges into the Irwell, Medlock and Irk rivers are responsible for a number of industrial contaminents found in the canal. Matters have improved since 1990, when the National Rivers Authority found the area between Trafford Road Bridge and Mode Wheel Locks to be "grossly polluted". The water was depleted of dissolved oxygen, which in the latter half of the 20th century often resulted in toxic sediments normally present at the bottom of the turning basin in what is now Salford Quays rising to the surface during the summer months, giving the impression of solid ground. Previously, only roach and sticklebacks could be found in the canal's upper levels, and then only during the colder parts of the year, but an oxygenation project implemented at Salford Quays from 2001, together with the gradual reduction of industrial pollutants from the Mersey's tributaries, has encouraged the migration into the canal of fish populations from further upstream. The canal's water quality remains low, with mercury and cadmium in particular present at "extremely high levels". Episodic pollution and a lack of habitat remain problems for wildlife, although in 2005, for the first time in living memory, salmon were observed breeding in the River Goyt (a part of the Mersey's catchment). In 2010 the Environment Agency issued a report concluding that the canal "does not pose a significant barrier to salmon movement or impact on migratory behaviours".

Despite the canal's poor water quality there are several nature reserves along its banks. Wigg Island, a former brownfield site east of Runcorn, contains a network of public footpaths through newly planted woodlands and meadows. Among the wildlife species found there are butterflies, dragonflies, kestrels, swallows and house martins. Further upstream the 200-acre (81 ha) Moore Nature Reserve, which is bisected by the de-watered Runcorn to Latchford Canal, comprises lakes, woodland and meadows. The reserve is open to the public and contains a number of bird hides, from which native owls and woodpeckers may be viewed. Near Thelwall, Woolston Eyes (a corruption of the Saxon Ees), is a Site of Special Scientific Interest. It is used as a deposit for canal dredgings and is a habitat for many species of bird, including Black-necked Grebes, Grasshopper Warblers, Blackcaps and Common Whitethroats. Great Crested Newts and Adders are present, and local flora includes orchids and Broad-leaved Helleborines. Diving ducks are regular visitors to Salford Quays, where species such as Pochard and Tufted Ducks feed on winter nights.