In order to avoid excessive pressure build-up in the hydraulic power network, a release valve was fitted beside the main hall of the powerhouse. A tall water fountain, the Jet d'Eau, was ejected by the device whenever it was activated. This typically happened at the end of the day when the factories switched off their machines, making it hard to control the pressure in the system, and to adjust the supply of pressurized water to match the actual demand. The tall fountain was visible from a great distance and became a landmark in the city. When an engineering solution was found which made the fountain redundant, there was an outcry, and in 1891 it was moved to its current location in the lake, where it operated solely as a tourist attraction, although the water to create it still came from the hydraulic network.