It is the source of the stream, Tykes Water, that runs north through Radlett.

It was built between 1795 and 1797 by the Grand Junction Canal Company, to control the water levels in the River Colne following the construction of the Grand Junction Canal, and was hand dug by French prisoners of war.

However, following an inspection of the dam in 2019, the current owners dropped the water level to reduce pressure on the structure.

[4] There have also been suggestions that public access will be reduced with the reservoir fenced off from Aldenham Country Park.

Nearby is the much larger Hilfield Park Reservoir, a nature reserve owned by Affinity Water.