[3] The upper reaches of the river are seasonal, with a perennial source derived from a number of springs located upstream of the village of Great Shefford.

The River Lambourn itself has a single perennial tributary, the Winterbourne Stream, which joins it at the village of Bagnor.

Here it is fed by several springs, two of which are close to the Goose Green road, forming a short stream that runs ten feet downhill into the river.

The river leaves the wood and enters Lambourn under a bridge crossed by the Goose Green Road, here it flows more quickly as the channel narrows to four to six feet across and six to eight inches deep.

Here the Lambourn forced its banks in July 2007 and flowed down the Newbury Road for over a hundred yards before rejoining the river.

The River Lambourn is almost unique for a chalk stream in southern England in that its flow regime remains near-natural in form; not being significantly modified by groundwater abstraction.

In the 1960s the long term water supply situation for London was regarded as vulnerable and one avenue investigated to rectify this was to use untapped water resources naturally stored in the chalk aquifer of low population density areas of south east England.

[4] Almost all of the infrastructure for the project (now known as the West Berkshire Groundwater Scheme) is still in place and maintained, albeit on a rather shoestring budget.