So, this photo is obviously a long exposure done in full day light. As usual for this kind of images i used my Hoya ND 400 filter and as often i added a 0.9 soft GND filter over the sky and snowy mountains.
The photo was done just before the end of the afternoon one day i was exploring the west side of the lake and i think i'll have to return in one or two months when the forest will be more green.
I started the day with a drive on the road of Semnoz mountain overhanging the lake but didn't found any very interesting place for landscape photography. The road offers some nice views on the lake but also on the high density of villages and houses all around.
After this little excursion in the mountain, i returned closer to the lake at one place i had noticed in the morning. I stayed there until dusk, did this image and a few other with softer colours (One can be seen here).