The Flashes (or lakes) are a legacy of the town's industrial past and were formed as a result of mining subsidence. Some of the flashes were partially filled with colliery waste and ash from the nearby Westwood Power Station. Ince Moss Colliery closed in 1962 and Westwood Power Station was demolished as recently as 1989. Natural colonisation and large-scale reclamation works have helped heal the industrial scars, turning the area into the amenity it is today.

The Reserve is part of a larger network of important wetland habitats, running for approximately 9km along the Leigh branch of the Leeds Liverpool Canal. These include Hey Brook, Abram Flashes SSSI, Pennington Flash Country Park and Hope Carr Nature Reserve.

Wigan Flashes habitats include large areas of open water, reedbed, fen, rough grassland, wet woodland and scrub. Over 200 species of bird, 15 species of dragonfly and 6 species of orchid have been recorded. The elusive Bittern is regularly recorded in the winter months and work to improve and manage the reedbeds is aimed at attracting this nationally rare bird to stay and breed.

The Flashes are known for their resident and overwintering waterfowl such as Grey Heron, Tufted Duck, Coot, Pochard, Goldeneye, Gadwall and Great Crested Grebe. Breeding birds include Reed Bunting, Willow Tit, Reed Warbler, Sedge Warbler, Common Tern and Water Rail.

The Flashes provide very important feeding areas for bats and support large numbers of Noctule and Dubenton's Bat.

The remaining colliery spoil and ash provide suitable conditions for a wide variety of wild flowers such as Common Spotted Orchid, Marsh orchids, Evening Primrose, Pale Toadflax and Vipers Bugloss. Less common species include Round-leaved Wintergreen, Marsh Helleborine and Yellow Birds Nest.