The current fiasco can be chalked up to bad planning and a ridiculously short air-drown time for Giant Sponges.
It began when I embarked to this wonderful little spot atop a cliff overlooking a fork in a major stream. My position was easy to fortify and has endured three Goblin sieges in a row while I fixed internal issues and continued to improve the quality of life in the fort. However, as soon as the sieges left and I fortified further out to begin the great Sponge Trapping Project, things began to go wrong.
My waterwheel system was all set up to drain the river (or so I thought). My miner was set to channel the block under the sponge. The door was in place to keep the pond from overflowing and the cage traps were open wide right beneath for a quick capture. All I had to do was pierce the dark underbelly of the river to drop the beast into a cage, and then turn on the machine to stop the river flow while I patched the hole.
The sponge died moments after capture. Apparently it airdrowned in 0.05 seconds. Then a foolish attempt to fix the hole from below ended with a drowned hauler. (He got drafted to remove a section of ramp.) Finally, my containment unit on the river failed, and spewed water all over the plains outside. None of my dwarves will go dismantle any portion of the machine so I can't stop it. I'm not sure how to fix this. Oh, and on top of that, the second giant sponge in the river airdrowned when I started the machine because I forgot I was going to try for both of them.
Ah well. At least there were no tantrum spirals this time. One drowned hauler is probably worth the lessons I'm learning. *sigh*
I had hoped this would be the fortress where everything went right, and all appearances seemed to indicate it was. ...but that's not the point, now, is it? The point is fun. Lots and lots of losing fun.
I shall now embark on a plan to test various methods outlined in the Child Care thread. 64/125 dwarves are children, so I think I have the population for it. *dark glare*