But water can be violent and dangerous, not only causing floods but also spreading disease. To tame it, riverbanks have to be strengthened. With the explosive population increase of the 19th century, the resources inherited from the Middle Ages became insufficient. Sources as far away as the Alps were tapped, and later - not without réticence - even lake water was pumped into the city and brought into the houses.
The demand for electrical energy increased, and to drive the turbines of new generating stations, and power cable railways, the Lake of Bret was created above Lausanne as a water reservoir. The hydroelectric schemes of the Alps date from the same period. After the generalization of electrical power, Lausanne's main rivers, the Louve and the Flon, served only as sewers, and they were covered over. But with the strict enfoncement of waste-water purification laws, most of the lakeside is again free of health hazards. The lake, however, has an incontestable place in Lausannes environment. Over a number of years quays, marinas, parks and pools have been constructed. The ancient fountains, too, lost their importance and many were demolished. Only nowadays is water being reintroduced into the city, mainly as an ornemental feature of the urban landscape.