River Mole

River Mole
Name	River Mole
Country	England
Counties	Surrey; West Sussex; Greater London
Length	80 km
Source	near Gatwick
Mouth	River Thames at Hampton Court
Basin size	480 km2

River Mole

The River Mole is a tributary of the River Thames flowing through Surrey, West Sussex, and the London Borough of Richmond upon Thames in southern England. It rises near Gatwick Airport and joins the Thames at Hampton Court Palace, passing through towns such as Dorking, Leatherhead, and Cobham. The river has shaped local transport, industry, ecology, and settlement patterns from the medieval period through the Industrial Revolution to contemporary environmental conservation efforts.

Course and Geography

The Mole's headwaters begin near Burstow close to Gatwick Airport and flow north-west through the Weald and the western end of the North Downs. It traverses chalk and clay geology including the Mole Gap—a notable valley between the Hog's Back and the North Downs Ridge—before passing Box Hill and skirting Dorking and Leatherhead. Downstream it flows past Fetcham, Westhumble, Bookham, Oxshott and Cobham to reach the Thames at Hampton Court Bridge near East Molesey. Tributaries include the Pipp Brook, the River Ember (via the Thames catchment), and several named brooks draining the Surrey Hills Area of Outstanding Natural Beauty. The river corridor intersects transport infrastructure such as the A24 road, the A3 road, the Kingston-upon-Thames rail lines, and the South Western Railway network.

Hydrology and Water Quality

The Mole's flow regime is influenced by chalk aquifers in the North Downs and impermeable Weald clay, producing highly variable baseflow and flashy storm response during Atlantic depressions and convective summer storms. Historic gauging at Leatherhead and Hampton Court records changes correlated with abstraction policies overseen by the Environment Agency and regulatory frameworks such as the Water Resources Act 1991. Water quality assessments reference parameters used by the Department for Environment, Food and Rural Affairs and the European Union Water Framework Directive (as transposed into UK law), tracking nitrates, phosphates, biochemical oxygen demand, and diffuse pollution from agriculture and urban runoff in the Mole Catchment. Remediation efforts involve partnership projects with organizations including the Surrey Wildlife Trust, the National Trust, and industry stakeholders like Thames Water.

History and Human Use

Human settlement along the Mole valley dates to prehistoric and Roman activity with archaeological sites connected to the Iron Age and Roman Britain near Box Hill and Dorking. Medieval mills powered by the Mole appear in manorial records tied to estates such as Hampton Court and local guilds. During the Industrial Revolution, watermills, tannery operations, and later gravel extraction altered channel morphology; extracted sites around Leatherhead and Bookham were later restored as wetland nature reserves. Transport history intersects with the river via coaching routes to Guildford and the development of the railway network by companies like the London and South Western Railway and the Brighton Main Line. Contemporary land use reflects conservation designations, statutory planning by local authorities such as Surrey County Council, and heritage management at sites like Hampton Court Palace.

Ecology and Wildlife

The Mole supports a mosaic of habitats—chalk stream reaches, lowland mixed deciduous woodland, wet meadows, and floodplain grazing marsh—important for species monitored under agreements involving the RSPB and the Wildlife Trusts. Fish assemblages include migratory species recorded by the Angling Trust and historic surveys by the Freshwater Biological Association; species of conservation note include brown trout and occasional European eel records. Riparian vegetation hosts invertebrates surveyed in partnership with the Natural History Museum, while floodplain pastures support breeding birds such as lapwing and snipe as well as bats monitored under the Bat Conservation Trust protocols. Non-native species management and habitat restoration have involved volunteers coordinated through local groups like the Mole Valley District Council environmental teams and conservation NGOs.

Flooding and River Management

The Mole has a well-documented flood history, with significant events recorded in the twentieth and twenty-first centuries prompting integrated flood risk management overseen by the Environment Agency and local authorities including Elmbridge Borough Council. Flood alleviation measures have included channel modifications, upstream storage proposals, and floodplain reconnection projects evaluated under National Flood and Coastal Erosion Risk Management policy. Historic defences near Hampton Court interface with heritage assets managed by Historic England and the Hampton Court Gardens stewardship. Climate change projections from the Met Office inform adaptive planning, while funding and governance often involve partnerships with agencies such as the Department for Environment, Food and Rural Affairs and local stakeholder groups.

Recreation and Culture

The Mole valley is popular for walking along routes promoted by the Long Distance Walkers Association and the Surrey Walking community, cycling on regional routes connecting Box Hill, and angling licensed through the Angling Trust and local clubs. Cultural associations include references in landscape paintings held by institutions like the Tate and regional literature by writers linked to Surrey and London artistic circles. Heritage sites along the course—Hampton Court Palace, Box Hill, and historic mills—attract tourism coordinated with bodies such as VisitEngland and local chambers of commerce. Annual events and volunteer conservation days are often organised with the Surrey Wildlife Trust and parish councils in towns like Dorking and Leatherhead.

Category:Rivers of Surrey