Leo writes*
Annecy is a city in eastern France whose lake and vibrant colours attract tourists from all around the country. Boasting a modest population of around 120 000 people, Annecy is a small city with seemingly not many problems in regard to water (Wikipedia). The main attraction is its lake “Lac d’ Annecy.” Often called the blue lung of the region, Lac d’ Annecy helps with droughts and other water issues (Annecy Lake saves local ski station from drought).
This has not always been the case, as the lake’s water was not always so clean. In the last century, the lake was overwhelmed with water demand from growth in development and population (Barraqué, 1986).
When the lake’s water was initially used in 1908, water quality was good enough to forego treatment (Barraqué, 1986). But quality started to deteriorate in the “entre-deux-guerres” (interbellum) period (Barraqué, 1986), as waste waters were discharged into the lake (Le Dauphine). Numerous carnivorous fish species started to disappear — notably the famous Omble chevalier.
After the liberation of France in 1945, growing industry and tourism increased water demand as well as pollution (Barraqué, 1986).
It was only ten years later that the alarm was rung in face of the dire situation. Charles Bosson the maire of Annecy at the time, expedited the complete renovations of sewer systems and water treatment for all municipalities around the lake (Barraqué, 1986). A new syndicate was created in order to address water quality, the SILA (Intercommunal Syndicate of Annecy Lake) which still exists to this day (Le Dauphine).
A completely new system was designed: a collection belt around the lake brought waste water to Annecy for treatment. This solution, although more costly for Annecy spread the costs and benefits of the new system between the communes of the lake. For the scale of the town at the time, this construction was massive: 47km of collection pipes, 190 km of new sewer pipes and a new purification facility (Barraqué, 1986). All for 2,275 billion French francs or the equivalent of 350 million euros today (Le Dauphine). With the system’s completion in 1976, water quality improved (Le Dauphine). Today, Lake Annecy has a reputation as the purest and cleanest lake in Europe.
Bottom Line: The modernisation of Annecy’s water management systems permitted its transition from a polluted body of water to one of Europe’s purest lakes.
* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂