UK ECN site. Upton Broad is a shallow lowland lake, formed by the flooding of peat diggings, which were abandoned in the 14th century. It has an area of 6.9ha and an approximate mean depth of 0.8m. The broad lies in the valley of the River Bure, at an elevation of less than 10m, but is isolated from the river system, and is groundwater fed, with some drainage from surrounding land. Geologically, the area is underlain by Quaternary deposits of Norwich Crag, with glacial till and outwash deposits at the surface. The broad forms part of the Upton Broad and Marshes Site of Special Scientific Interest (SSSI). It is considered to have been relatively unaffected by the eutrophication that has damaged most of the lakes in the region, and supports a population of the nationally rare aquatic macrophyte Najas marina. The broad is surrounded by a band of alder carr (wet woodland). To the north of the broad are drained grazing marshes forming part of the Broads Environmentally Sensitive Area (ESA), and to the south the catchment is given over to the more intensive arable agriculture. The broad is used for angling by a private club; there is no other public access to the lake. [Photo copyright Norfolk Wildlife Trust]