Rostherne Mere | |
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![]() View across the mere
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Location | Cheshire |
Coordinates | 53°21′14″N 2°23′13″W / 53.354°N 2.387°WCoordinates: 53°21′14″N 2°23′13″W / 53.354°N 2.387°W |
Basin countries | United Kingdom |
Surface area | 48 ha (120 acres) |
Average depth | 30 m (98 ft) |
Designated | 24 July 1981 |
Rostherne Mere is a natural lake in Cheshire, England. It is the largest of the Cheshire meres with an area of 48 hectares and a maximum depth of 30 metres. It lies to the north of Rostherne village and to the south of the M56 motorway. Because of its importance for wildlife, the lake, together with neighbouring areas of woodland and pasture, has been declared a national nature reserve, a Ramsar site and a Site of Special Scientific Interest covering 152.9 hectares.
The lake lies on thick sedimentary deposits of glacial origin above marl and salt-beds. It was probably formed by a combination of retreating glaciers creating a kettle hole and subsidence caused by the underlying rock salt dissolving away. The lake is fertile and base-rich with high levels of phosphate, nitrate and ammonia. Nutrient levels have risen as a result of inflow from surrounding farmland and streams and because of the droppings from large numbers of roosting birds.
Large numbers of ducks winter on the lake including tufted duck, pochard, goldeneye, teal and wigeon. Roosting birds include up to 10,000 black-headed gulls, 1000 common gulls and 300 cormorants. Breeding birds include great crested grebe, reed warbler and sedge warbler while lesser spotted woodpecker and little owl occur in the surrounding area.