River mole (Rio Mole) is located between Leatherhead and Fetcham in Surrey.

Leatherhead Rio Mole

The river mole is a tributary of the river Thames in England. Rio Mole tributaries includes Ifield brook, Earlswood Brook, The Rye which drains Ashtead, Pipp Brook, and Gatwick Stream.

River Ember is its major distributary. The river gives its name to mole Valley in the surrey district. The molebranches into the North Downs between Dorking and Leatherhead, where it crosses into a steep-sided valley called the mole gap.

Around the second half of the 20th century the water became highly polluted, but by the year 1995 the water quality became greatly improved, and presently, the mole boasts of great diversity of fish species in any river in England.

River mole (Rio Mole) is located between Leatherhead and Fetcham in Surrey

Its geology consists of an upper mole (this is dominated by a single broad terrace which runs continuously from the entry to the mole gap as far south as Tilgate forest), the mole gap (most holes are difficult to observe in times of normal or heavy flow and are susceptible to sitting up as new holes are continually being formed), and the lower mole (the depth varies from 2.5 to 7m and the lower layers are mostly highly cemented and compacted together with oxide and upper layers are loosely packed with sand and angular flints.

The river has captivated the mind of many poets and authors, most particularly in very hot summers when the river channel becomes dry in-between Dorking and Leatherhead. The marsh frog species is commonly found in the tributaries around Newdigate and Gatwick and also in the upper mole. There has not been evidence that the habitation of frogs have a deleterious effect on other indigenous amphibians there.

The River Mole is said to have the most diverse fish population than any river in England. There is abundance of coarse fish such as eel, brown trout, and brook lamprey in the Gatwick stream. In the mole gap in-between Dorking and Leatherhead the river has a large population of barbell, brown trout, dace and chub. Both barbell and brown trout are extremely sensitive to pollution and water quality.

During the period of the Second World War, several sites along the course of the mole were fortified for the defense of London to prevent invasion from the south. Between the Box Hill and Betchworth, the north bank of the river mole was made steeper and established to prevent wheeled devices from crossing.

The river crossing at Sidlow Bridge was heavily protected and the line of pill boxes was erected on the north bank of the river. Also, anti-tank dragon’s teeth made of concrete were built on either side of the river, a short length of the bridge as an obstacle for armored vehicles.

There are three bridges in Leatherhead of which the 14 arch Leatherhead Town Bridge is the most famous. The first bridge on the site was constructed around the late middle ages and was later rebuilt and enlarged around 1783.

A restoration project was executed much later in the memory of the Canadian servicemen who were billeted in the manor in the heat of the Second World War.