Later Kettlemill was used as a coal-fired electricity plant but was eventually demolished to make way for the offices of the Local Drainage Board.

The site is now occupied by the offices of the Caldicot and Wentloog Levels Internal Drainage Board.

The mill ceased production a few years after this event, probably as a consequence of the Drainage Board's actions.

Many of these are now managed by the Caldicot and Wentlooge Levels Internal Drainage Board.

The mill became derelict and was demolished in 1954 by the Drainage Board in order to improve control of the river levels.

The Internal Drainage Boards also had to upgrade some of their pumps to cope with the extra volumes of water.

The Drainage Board created in 1918 had no powers to address navigation issues, and there were six bodies responsible for the river below Denver in 1913.

The island was connected to the water supply system by the then Metropolitan Water Sewerage and Drainage Board in the 1980s.

The upper reaches, to below Snarford Bridge and most of the tributaries below that are maintained by the Drainage Board.

The Drainage Board were responsible for constructing six pumping stations between 1975 and 1979.