Ah.
It's important to keep in mind that beavers aren't dwarves. Not only can they all swim, they *enjoy* it. So instead of building bridges across streams, all you need to do (and all you should do) is build a stairs down into the water, a path along the riverbed, and a stairs on the other side.
This gives your citizens a mood bonus from having wet fur. Which is not, you might think, a penalty.
This also means that when you plan out engineering projects involving redirecting the flow of water, you don't have to wait until there is no water flowing so that you can do your digging/building while it's safely dry, so as to not risk drowning your citizens.
You can just order floodgates and dams built right from the get-go. They'll happily swim out there and build them, provided you've placed a path.
@jpetazzo yeah, that part is also a little irritating.
Why can they build buildings on top of other buildings, but then complain they can't reach the door? If you can't access the building, how did you build it in the first place!?
There are a few quality-of-life issues I'm finding with it, this is one of them. And then you can't move the building, you have to deconstruct it, and that doesn't refund the full building amount. Which is rather archaic.
@jpetazzo @Hyperlynx rule of thumb: 1 block above their head is okay. But sometimes not ;)
Building down goes much further.
Len
Jérôme Petazzoni
Erik