Vattenundersökningar - Vägledning för hydromorfologisk karakterisering av sjöar
This European Standard is applicable to lakes, which are water bodies occupying one or more basins with surface areas greater than 1 ha (0,01 km2) and maximum depths (at mean water level) greater than 1 m. All types of permanent lakes, including natural, modified and artificial, freshwater and brackish, except for those systems which regularly connect to the sea, are included in this European Standard, though canals are excluded. Based on these criteria, it can be estimated that there are at least 500 000 natural lakes across Europe, most of which are located in the glaciated landscapes in northern and western provinces and in Scandinavia. Lakeland districts also occur locally in areas such as the Danubian plain and around the Alps. Elsewhere, naturally occurring lakes are relatively sparse and in such areas reservoirs or pits are more common. This European Standard is designed to: a) support environmental and conservation agencies in meeting the monitoring requirements of the WFD (Article 8, Annex II and Annex V); b) generate data sets appropriate for monitoring and reporting of Natura 2000 sites designated under the Habitats Directive and the Birds Directive; c) provide information supporting other environmental reporting requirements (e.g. in relation to biodiversity or environmental impact assessment); d) support lake management and restoration initiatives.