ECN site code: L05
ECN monitoring by: UK Centre for Ecology & Hydrology

Esthwaite Water is a natural lake situated in a glacial valley and is generally agreed to be the most productive or eutrophic lake in the English Lake District. It lies approximately 65 m above sea level and has an area of 1 km2 and a maximum depth of 15.5 m. The catchment area is 17.1 km 2 and the hills are composed geologically of Bannisdale slates and grits. The surrounding land is used chiefly for agricultural purposes and forestry.

The lake is a grade 1 Site of Special Scientific Interest (SSSI) and has been a designated "Ramsar" site since November 1991. The diverse aquatic invertebrate fauna includes a number of species with restricted distributions in Britain, one of which is the flatworm Bdellocephala punctata. The slender naiad Najas flexilis, a plant listed as Nationally Scarce, has been found in Esthwaite Water.

There is more information about Esthwaite Water on the UKCEH website.