the site is the largest area of freshwater marsh in greater london. it is very diverse, with large areas of reed sweet-grass, common reed swamp, wet neutral grassland and tall fen. these habitats have a wide variety of invertebrates and breeding birds. invertebrates include sixteen nationally scarce fly, beetle dragonfly and cricket species. there are two nationally rare red data book species, the hoverfly "anasimyia interpuncta" and the scarce emerald damselfly "lestes dryas". 61 species of bird regularly breed on the site, such as the common redshank and the northern lapwing. common cuckoos exploit the nests of reed warblers and sedge warblers. havering council has raised the water level and reintroduced grazing to protect the wetland.