The River Till rises near Tilshead on Salisbury Plain in the English county of Wiltshire.

It flows for about 14 km (9 miles) south and south-east, through Orcheston, Maddington, Shrewton, Winterbourne Stoke, Berwick St James and Stapleford, to join the River Wylye.

[2] The whole length of the Till has been designated as a Site of Special Scientific Interest, as its vegetation includes water crowfoot which provides habitat for fish and snails.

[5] The Environment Agency measures the water quality of the river systems in England.

There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish.