Venice’s has two problems with water now. Flooding (which happens about 100 days a year now – in varying degrees) or low water. As Steven points out, the low water is just as bad. Almost every building in Venice is built on wooden pilings driven down to rock at the bottom of the lagoon. The low water exposes the pilings which promotes rot. Most of the pilings in the city are hundreds (if not over 1000 years old in some cases) of years old and have not been exposed to air since their placement. I believe I’ve read that St Marks rests on upwards of a million pilings.

I’ve gotta go before the city sinks into the lagoon…

Venice is, I’m told, not quite as glamorous as it’s portrayed to be. The problem is that the water gets fetid. Sometimes it’s worse than that; the place gets swarmed with insects. (I’ve seen film and it looked awful.) It’s because it’s in a salt water lagoon and they can’t control the water.

I haven’t been there, but I’ve been to Amsterdam. The canals there are managed much better. It’s fresh water in the canals, and they have control over the whole system and a convenient river near by, so they flush and replace the water six times a week. That means it doesn’t get disgusting. They also carefully control the water level, so flooding isn’t a problem.

Oddly enough, having the water be too low is also dangerous; a lot of the older buildings are on wooden pilings. As long as the wood stays wet, it will keep. But if the wood is allowed to dry out, it will start to rot. So that’s another reason why they have to maintain the water level carefully.