River Loddon The River Loddon is a river in the English counties of Berkshire and Hampshire . It is a tributary of the River Thames , rising within the urban area of Basingstoke and flowing to meet the Thames near the village of Wargrave . The river has a total length of 28 miles ( 45 km ) and , together with its tributaries , drains an area of 1036 km² . The River Loddon rises at West Ham Farm in Basingstoke , and in its first mile flows under the Festival Place shopping centre that forms the main part of the central area of that town . The river then passes close by the village of Old Basing and the ruined palace of Basing House . Leaving the environs of Basingstoke behind , the river flows north through open north Hampshire countryside and passes near by the village of Sherfield on Loddon . North of Sherfield the river passes through the ornamental grounds of Stratfield Saye House , the home of the Dukes of Wellington since 1817 . Entering Berkshire , the river passes the village of Swallowfield . Just north of Swallowfield the River Loddon is joined by the River Blackwater which adds substantially to its flow . The river then flows close to the east of the Berkshire suburbs of Earley and Woodley , to the west of Winnersh , and through Dinton Pastures Country Park . Shortly after this , near the village of Hurst it is joined by the Emm Brook . The river then flows close to the village of Twyford and is joined by the St Patricks Stream , a backwater of the River Thames . About a mile further on it flows into the main channel of the Thames , just downstream of Shiplake Lock and close to the village of Wargrave . Whilst chalk underlies much of the River Loddon 's catchment area , it only appears at the surface at either end of the river , near Wargrave and Basingstoke . For the rest of its course the chalk lies beneath the Reading Beds and London Clay . The terrace gravels of the Loddon valley have been extracted in a number of places , including the lakes within Dinton Pastures Country Park . The catchment area of the River Loddon encompasses urban populations in Basingstoke and eastern Reading , whilst the urban areas of Aldershot , Fleet , Camberley and Farnborough all lie within the catchment area of the tributary River Blackwater . As a consequence the Loddon receives treated sewage effluent at nine locations , one just downstream of Basingstoke , a second at Wargrave , and seven indirectly via the Blackwater . See also Rivers of the United Kingdom References ^ a   b   c The River Loddon and the Emm Brook . Wokingham District Council . Retrieved on March 30 , 2006 . ^ Explorer Map 144 - Basingstoke , Alton & Whitchurch . Ordnance Survey ( 2005 ) . ISBN 0-319-23606-4 . ^ Explorer Map 159 - Reading . Ordnance Survey ( 2006 ) . ISBN 0-319-23730-3 . External links Map sources for the source of the River Loddon . Map sources for the mouth of the River Loddon . Categories : Rivers in Berkshire | Rivers in Hampshire | Tributaries of the River Thames The River Loddon and the Emm Brook http : //www.wokingham.gov.uk/your-community -- district/countryside-service/countryside-sites/rivers Wokingham District Council March 30 2006 SU619520_region : GB_scale : 100000 Map sources SU778786_region : GB_scale : 100000 Map sources 