Three Rivers is a local government district in Hertfordshire adjoining Greater London and Watford and forming part of the Greater London Urban Area. The district was formed on 1 April 1974 by the merger of Rickmansworth Urban District and Chorleywood Urban District with part of Watford Rural District. With no obvious name for the district, it was named "Three Rivers" after the Chess, Gade and Colne. More information on the Wikipedia page [1]. The website is [2].