The trains are still there. Years ago National Geographic went to the canal and sent divers down. Most of the equipment, from small 0-4-0 porters, to the large steam railcranes, still sit on the bottom of the deeper parts of the canal. In fact, there's one whole train still coupled to its cars that sits on the tracks there.
This is a picture of one of the locomotives being recovered from the bottom of the lake.
http://www.czimages.com/CZMemories/frtrain/lakeloco.jpg
This is a pic of the plans for it, if anyone wants to build it:
http://www.czimages.com/CZMemories/frtrain/icc.jpg
A quote from a scuba diving page:
"Suddenly, something large and dark seems to rise up before me—it is the rusted cab of the engine! As I get closer, I see that is exactly what it is, a hulking coal-fired phantom of iron from another century. Trailing behind it is a line of gondola cars, forever bereft of their loads of rock and soil....I swim in and out of the cab and then, my air dwindliing, begin my slow descent back into the present, leaving the train to dissolve behind me in the haze. As I do, I think how the movement of earth and the damming of rivers have birthed islands from drowned mountaintops, haunting visions of Gallic glory from submerged river valleys."
