River Mimram

The river valley known locally as the Mimram Valley is named after the River Mimram, which rises from a spring to the north-west of Whitwell, in North Hertfordshire, England, and makes its confluence with the River Lea near Horn's Mill in Hertford. At Whitwell there are watercress beds which have existed since Roman times and these are fed by the same springs. The valley extends northwards where it becomes known as Lilley Bottom. Other sections of the valley are known as Kimpton Bottom and Codicote Bottom. After flowing through Whitwell, Kimpton and Codicote, the river flows through the middle of Welwyn village before heading between the modern and older Digswell settlements, and then running cross-country until it reaches the River Lea at Hertford.

Although a dry valley to the north, it has been known in particularly wet years for the River Mimram to be extended for several miles by springs in the upper valley. In 2001, in a neighbouring valley to the west a village was flooded. The Valley is the furthest east of all the Chiltern Hills valleys.

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