Correspondence for Christchurch Drainage Board. Includes outwards correspondence in letterbooks 1922 – 1992 and inward correspondence files 1906 – 1987. The correspondence in this series is indexed across two separate indexes:

Inwards correspondence: CH362 contains index cards for filing numbers 21/ - 32/ which covers c.1919-1932 CH658 contains index cards for filing numbers 32/ onwards which covers 1932 onwards. Note that there is content across both card indexes covering c.1920-1930, so for this time period both indexes will need to be used together to ensure all references are located.

Outwards correspondence: CH362 contains index cards for letterbooks with filing numbers 30-200 which covers c.1926-1965 CH658 contains index cards for letter books with filing numbers 200 onwards which covers 1965 onwards. Note that there is content across both card indexes from c.1960 so for this time period both indexes will need to be used together to ensure all references are located.