The Trout Beck is a headwater stream of the Tees which drains Great Dun Fell, Hard Hill and Knock Fell in the North Pennines. The ECN sampling point is at 535m altitude and the catchment above this covers 1146 ha, rising to 848m altitude. The geology is alternating strata of Carboniferous limestones, sandstone and shales. Blanket peat covers 90% of the catchment with skeletal soils towards the fell tops and small areas of limestone soils and alluvial soils. Vegetation is dominated by ling heather (Calluna vulgaris), cotton grass (Eriophorum spp) and Sphagnum moss. The catchment lies in Moor House National Nature Reserve which is owned by Natural England. Discharge is measured at an Environment Agency gauging station. The pH of Trout Beck averages 6.2 although there are wide fluctuations associated with the discharge. The site has a long history of ecological research.

Trout Beck was the first ECN Freshwater Site to be co-located with an ECN Terrestrial site. Its catchment is entirely within the Moor House-Upper Teesdale Terrestrial Site.