The Wey North branch rises in Alton in Hampshire and runs eastwards through Upper Froyle and Bentley, turning southeast at Farnham to Tilford. This branch was originally the upper catchment of the River Blackwater; this "early river Wey" captured waters from as far as Tilford. When this branch was blocked at Farnham, the flow spilt over into areas such as Elstead; for a short section past Waverley Abbey the flow has become reversed. The Blackwater remains as a much shorter river to the north of Farnham, with a wind gap between it and the Wey.
Wey South
The Wey South branch commences in two shorter rivers leading from separate sources. One is at Blackdown, south of Haslemere, and runs through Liphook, Bramshott, Passfield, Standford, Lindford and Frensham to Tilford. The other rises at Inval, below Gibbet Hill, Hindhead in the civil parish of Haslemere. This joins the Blackdown-source south branch west of Haslemere. Other smaller tributaries of the south branch are Cooper's Stream and the River Slea.
Combined river
From Tilford the river runs through Elstead, Eashing, Godalming, Peasmarsh/Shalford, Guildford, Send, Old Woking, Pyrford, Byfleet, New Haw and forms the Addlestone/Weybridge border between Hamm Court and Whittet's Ait respectively. From Godalming the river is intertwined with the Wey and Godalming Navigations. The of towpath of the lower section is open to pedestrians. It joins the River Thames between Hamm Court and Whittet's Ait facing a weir stream of Shepperton Lock.
Tributaries
The River Ock joins at Godalming, Cranleigh Waters and the River Tillingbourne at Shalford and the Hoe Stream at Woking.
History
The river has long been used as a source of power for mills, and many are recorded in the Domesday Book. Between the 17th and 19th centuries there over 40 mills on the river and more on its tributaries. At various times they have been used for grinding grain, fulling wool, rolling oats, crushing cattle cake, leather dressing, paper production and gunpowder manufacture. Willey Mill, at Farnham, was still in use in 1953. Headley Mill is still in commercial operation. Guildford Town Mill, though no longer used for milling, still harnesses the power of the river to generate electricity. During the seventeenth century, the river was made navigable to Guildford and extended in the eighteenth century to Godalming. The Basingstoke Canal and Wey and Arun Junction Canal were later connected to the river. The navigable sections are now owned by the National Trust.
Natural environment
Wey Valley is a term for the narrowing basin of the River Wey before it empties into the River Thames. Much of the upper reaches of the river are within the Surrey Hills Area of Outstanding Natural Beauty. The river passes through a variety of habitats including heathland, woodland and watermeadow, resulting in a diversity of wildlife. There are Sites of Special Scientific Interest and Nature Reserves along the river. The area of the aquifers which drain steeply to the river is great so, as with the Mole, in its natural state much of the flood plains were prone to regular flooding. This has been greatly reduced by flood alleviation, upstream lakes such as Frensham Great Pond and, inadvertently, the Wey Navigation. Urban lowest parts of Godalming, Byfleet and Weybridge saw extensive flooding in the exceptional Winter storms of 2013–14.
Water quality
The Environment Agency measure water quality of the river systems in England. Each is given an overall ecological status, which may be one of five levels: high, good, moderate, poor and bad. 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, and chemical status, which compares the concentrations of various chemicals against known safe concentrations. Chemical status is rated good or fail. Water quality of the River Wey in 2016:
Section
Ecological Status
Chemical Status
Overall Status
Length
Catchment
Channel
Heavily modified
Heavily modified
Surrey rivers
Aside from the River Thames, which does not belong to any one county, the river is one of the two main Surrey rivers, alongside the Mole. Until its incorporation into London in 1965, next in order of size was the River Wandle. Then follow the River Bourne and the River Bourne, Chertsey which merge. They have sources in Surrey and Berkshire. Surrey's Epsom area is drained by the Hogsmill River, most of which is in outer London.
