The Hamble Brook flows through Hambleden Valley for approximately 6.8 km (4.2 miles) from its source near Fingest to its confluence with the River Thames at Mill End, approximately half way between Henley and Marlow, although during the very wet winter of 2014 it rose to west of Turville running down the village main street until it found its natural path just before Fingest. The Hamble Brook is a winterbourne throughout its entire length and sometimes does not flow at all, a quirk of the local geology.
The geology is of Middle Chalk valley slopes with Upper Chalk valley tops. River Terrace Deposits occur on the main valley bottom following the course of the Hamble Brook There are a number of calcareous grassland SSSIs on the valley sides nearby, including Turville Hill, Wormsley Chalk Banks in proximity to Turville and Fayland Chalk Banks south of Skirmett. Aston Rowant on the northern edge of the area is a designated Special Area of Conservation (SAC) and a Site of Special Scientific Interest (SSSI), one of the best remaining examples in the UK of lowland juniper scrub on chalk.
The Hamble Brook suffers badly from cattle poaching of the river bank and pollution from cattle defecating in the stream as fencing only is present for part of its length. The edges of the banks have been trampled down due to many years of cattle grazing causing erosion that leaks soil and sediments into the watercourse. At some spots the entire width of the Brook is under a deep blanket of sediment covering the gravel that means as a habitat it is of very limited value to wildlife. The Brook particularly, at its lower end, has also been moved away from its original channel.
The Hamble Brook is classified by the Environment Agency as a river and designated Hydromorphologically as not being an artificial or highly modified water body. The total catchment area is 45.1 km2 (17.4 miles2).
Environment Agency Classification for the Hamble Brook
|2009 Cycle 1||2016 Cycle 2||Objectives|
|Water body status overall||Poor||Poor||Good by 2027|
|Ecological Status||Poor||Poor||Good by 2027|
|Chemical Status||Does not require assessment||Good||Good by 2015*|
*As reported in Environment Agency's WFD Classification Status Cycle 2 v3 data set published 18th May 2017.
The actual Chemical Status of the Brook is good but as can be seen from the table above, in 2016 the Environment Agency classified the Ecological Status of the system as Poor overall primarily due to a Poor Biological Quality Component mainly related to low invertebrate populations for all the reasons discussed above. The chemical classification was Good in 2016. The overall water body status for the Hamble Brook is predicted to be Good by 2027.
You can find out more about the classification of rivers in our catchment by using the Environment Agency’s Catchment Data Explorer