Mimmshall Brook

Mimmshall Brook is a 9.8 kilometres (6.1 mi) long stream (brook) in Greater London and Hertfordshire, England. Rising from two sources—one in Hertsmere, Hertfordshire, and the other in Arkley, London Borough of Barnet—the brook drains into a catchment area of 52 km2 (20 sq mi) at Water End Swallow Holes, Welham Green, North Mymms. It is a tributary of the River Colne.