The Valve House

This innocuous building situated on the main dam at Ruislip Lido controls the water level. 

There is a level gauge in the Lido towards the dam in one "corner".

The water level is kept much lower than in the days the Lido was used both as a canal feeder and in the 1960's with it was used for water skiing etc. This is because by keeping it low in the event of and localised flooding and excess water feeding in the Lido (Mainly from Northwood) it can be used as a buffer to take up the extra water and then it can be slowly released afterwards.

Water flows in to Cannon Brook and passes under Bury Street and eventually in to the River Pinn