The Site is the largest spring-fed fen in Ireland. The fen is largely intact and the Site’s habitats include semi-natural fen, damp grassland, woodland and open water. The fen supports a well-developed and specialized range of plants and animals, including a number of rare or threatened plants, invertebrates, birds and mammals. There are several rare plant species including fly orchid (Ophrys insectifera) and woolly feather-moss (Tomentypnum nitens), which is a boreal relict species. There are a number of notable invertebrates (mainly Diptera species) and this is the only site in Ireland and Europe to support the three species of whorl snail listed on Annex II of the European Union Habitats Directive (Geyer’s whorl snail, narrow-mouthed whorl snail, and Desmoulin’s whorl snail). The Site supports an indigenous fish, the brook lamprey (Lampetra planeri). Other threatened species include European otter (Lutra lutra) and marsh fritillary butterfly (Euphydryas aurinia). Rewetting of an area of reclaimed land has enabled the devlopment of open water habitat, increasing the value of the Site for waterbirds. Their numbers are small but include mallard, snipe and little grebe. Occasionally, rare bird species such as marsh harrier and reed warbler visit. The main threats are related to the inflow of urban wastewater and to livestock farming.