Upper Middle Thames (Wallingford to Caversham)


© Crown copyright and database rights 2017 Ordnance survey

Within the South Chilterns Catchment, the Middle Thames is the section that runs from the confluence of the River Thame with the Thames just north of Wallingford, south to Reading, then north and east finally to Cookham near Maidenhead. The Thames skirts around the western edge of the Chilterns that is designated an Area of Outstanding Natural Beauty (AONB). This Middle Thames reach has been divided into two parts Wallingford to Reading and Reading to Cookham.

Goring Gap
Goring Gap © FWR

This northern section of the Middle Thames commences at the confluence with the River Thame just below Dorchester, continuing south past Benson and Wallingford, through the Goring Gap (where the Thames divides the Chilterns from the Berkshire Downs to form the Goring Gap) then running in a large sweeping arc around the western edge of the Chilterns to Reading, a total distance of 39.4 km (24.5 miles).

A number of tributaries enter the Thames in this section, the Mill Brook and Bradford's Brook system at Wallingford, the Cholsey Brook south of Wallingford, the Berrick Stream and Lady Brook system as well as the Ewelme Stream both near Benson. Two major tributaries that also enter the Thames in this section. They are the River Pang at Pangbourne and the River Kennet at Reading. The area is also characterised by a number of other small “winterbourne” streams that only flow during periods of heavy rainfall and high groundwater levels.

The Thames valley here is a mixture or rural land (mainly open pasture and flood meadows) and urban areas such as Wallingford, Pangbourne and Reading, This reach of the Thames is dominated by Chalk geology, with the Vale of White Horse, Berkshire Downs, Chiltern Chalk Scarp and South West Chalk aquifers all contributing to flows. There are over 12 wetland/nature reserves in the area managed by The Earth Trust at little Wittenham, the Withymead Nature Reserve at Goring, Beale Wildlife Park, the Chiltern Society and the Berks, Bucks & Oxon Wildlife Trust (BBOWT). The Thames is also an important river for recreation in the form of course fish angling, boating (both commercial and leisure), canoeing, rowing, sailing, and rambling.

The Environment Agency have Hydromorphologically designated the whole of the Lower Middle Thames as a heavily modified river as it is managed for navigation with a series of locks breaking up the natural flow of the river and effectively making it a series of managed impounded reaches. In addition, certain sections of the river banks have been steel sheet piled to prevent erosion, particularly from boating traffic, that has channelised the river in many sections. The total catchment area of Upper Middle Thames is 186.5 km2 (72.0 miles2).

Environment Agency Classification for the Upper Middle Thames (Wallingford to Reading)

  2009 Cycle 1 2016 Cycle 2 Objectives
Water body status overall Moderate Moderate Moderate by 2015*
Ecological Status Moderate Moderate Moderate by 2015*
Chemical Status Good Good Good by 2015*

*As reported in Environment Agency's WFD Classification Status Cycle 2 v3 data set published 18th May 2017.

The Ecological Status was judged only as Moderate due to firstly, the Moderate classification for the Invertebrates, and secondly to both Phosphate levels and a specific pollutant – Triclosan (Triclosan is an ingredient that is added to some antibacterial soaps and body washes, toothpastes, and some cosmetics products intended to reduce or prevent bacterial contamination). The Phosphate and Triclosan are suspected to arise from a number of sewage discharges along this reach of the river. There are also flow pressures resulting from groundwater abstractions. The overall water body status for this section of the Middle Thames is predicted to remain at Moderate.

You can find out more about the classification of rivers in our catchment by using the Environment Agency’s Catchment Data Explorer

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Berrick Stream
Cholsey Brook
Ewelme Stream
Hamble Brook
Hughenden
Mill Brook
The Pang
Sonning Eye
Sulham
Lower Middle Thames
Upper Wye
Lower Wye