With all that found wich goes in the fortress, we diffinitaly need to have toilets. Otherwise, there migh be some brown blood like boods, spawning Myasm...
They could either be emptyied with a dwarf carrying a bucket. But it would make him quite unhappy. I might also be possible to connect it directly to the river, or to a channel. (thus changing the color of the river in a slighy muddier water)
Throwing that into the river would seriously upset the frogmen over long time (so building a steam shield would be quite usefull), or it could somehow be used to mix with the water when laying mud in farms (and thus fertlizing it). To do that, you'd need a fairly big tank to store some of these "refuse" over the year. Lets say you need 2 or 3 poo units to fertilize a square of farm.
Some nasty events could be leachate into your fortress leading to some myasma, floodgate being blocked, requering it to be cleaned (very uncomfortable to do for the dwarf : The little should definitally not be at the verge of thrawing tantrums).
Or I'll let you imagine all sorts of humiliating traps. (But I don't know how it would change anything with the baddys. Maybe make them slowier, or have them throw up ?)
Well, I haven't checked all bloats, and req. But there might already be something like that being prepared...
Edit : Of course, If not too far from the forest (or not sick from any kind or rotten food), and if the gate doors are not closed, the dwarfs could run to hide behind a tree.
Drinking from river which has been polluted upstream might of course make the dwarf get sick. (However If I understood well the "dieing" of the water from blood is permanent. In that case it should not : One poo, the water truns brown for a while. The more you add, the longer it lasts)
[ August 26, 2006: Message edited by: flap ]