UK ECN site. The River Stinchar is situated in South Ayrshire. It rises close to Loch Doon and flows for 46km before entering the Firth of Clyde at Ballantrae. It has a catchment area of 340km2 and its average flow is 11.2 cumecs. The catchment is largely rural with only a few small and scattered communities. Farming is mostly dairy cattle and sheep rearing, and there have been some pollution problems associated with the latter in particular through spillages of sheep dip chemicals. The upper part of the catchment is extensively forested with conifers for commercial use. The granitic geology and the maturity of the trees have resulted in low pH values in the uppermost routine sampling point. Part of the flow of the upper reaches of the river is diverted by an aqueduct to feed water into the Loch Braden water supply reservoir. The ECN site is situated in the lowest reach of the river where the acidity has been buffered by the base cations in the lower part of the catchment.