It rises in Langley, flows through Boughton Monchelsea, Loose and enters the Medway at Tovil.

The river valley is deep sided, and there is much evidence of the paper and wool trades which once flourished here: the stream has been dammed in many places, resulting in many mill ponds.

Owing to the purity of the stream, paper making rose in importance in the nineteenth century.

It had an overshot waterwheel driving three pairs of millstones, and was working until the First World War but subsequently demolished.

The present building dates from c. 1880 and last worked c. 1892, Mrs Marsham, the owner gave notice to the miller that she wished to terminate his tenancy in April 1891.

The eventual granting of the Light Railway Order involved a tunnel which was considerably longer than that which was originally proposed, a fact which pleased Mr. Green, who prophesied that "the longer the tunnel the less chance the line would be built."

[2][6][8][9][10][11][12][13] TQ 756 541 51°15′32″N 0°30′55″E / 51.259018°N 0.515263°E / 51.259018; 0.515263 (Upper Crisbrook Mill) The seventeenth-century structure latterly had a cast iron overshot waterwheel driving pumping machinery, working until the 1960s.

The derelict waterwheel survived in the early 1970s and has now been restored, the mill buildings being house converted c. 1975.

Due to the large number of ponds, the Loose stream and extensive areas of semi-improved grassland, it is a haven for wildlife.

The water quality of the stream has been classified by the Environment Agency as ‘very good’ close to its confluence with the River Medway at Tovil.

It then becomes a series of long narrow fields bordered by scrub/woodland on the upper edges of the Valley, which are very lightly grazed by cattle.

This section of the Valley is owned by the Loose Amenities Association and is managed purely for wildlife, landscape and recreation.

[17] Chrisbrook ponds host moorhens, coots and tufted duck, Canada geese visit in the mornings and egrets and kingfishers eat the fish.

Winter time is a good time for birdwatching with kingfisher, little grebe, little egret, water rail, ring-necked parakeet, grey wagtail, mallard, moorhen, black headed gull, grey heron and jackdaw regularly seen.

On the dry calcareous semi improved grasslands of the upper valley meadow vetchling, meadow-pea, and bird's-foot trefoil are found.

It is an extremely valuable habitat and supports species such as dormouse, warblers and butterflies.

The woodland of the Loose Valley contains species such as oak, ash, sycamore, hazel and sweet chestnut.