So the bike path had a small puddle across it this morning. At this point the path has fences on both sides as it goes under an overpass, so no way around. I start through only to quickly realize two things, the puddle is deep, like top of my tires deep; and the puddle is in fact part of the nearby river the bike path follows.

Froze my little toes the rest of the way. There were a total of four places where the river had overrun its banks, but the other three I managed to go around. And to think I almost left the neopreme long underwear off this morning.

Question: How bad is it for my hubs/bottom bracket/deraileurs to be submerged for a good 30 seconds?

Do you do any special maintenance after going through an "above the hubs" puddle?

at minimum take the seatpost out and drain any water that could have gotten in that is now pooling at your bottom bracket
other than that, I would just take everything apart and clean and regrease hubs and bearings. if your bike is old and has a freewheel, you should probably oil that as well - there's usually an oil port for squirting in oil.

If you have cartridge bearings in the BB and hubs, you probably don't need to worry much (and there's also not much you could do if you wanted to). If you have cup & cone bearings, it would probably be prudent to disassemble, clean, and repack them. If you don't already know how to do this with cup and cone axles and BBs, you would probably be best off finding someone that has some experience to show you how to go about it.

Your deraileurs should be fine with just spraying a little lube on the moving parts. If you are feeling ambitious, you could remove the idler wheels from the rear DR and clean and re-oil the bushings.

I would also be a little worried about your chain. Any air pockets likely have had water sucked into them as the chain flexed around the sprockets and rear deraileur. If you care deeply for the chain (if it's expensive and brand new, for example), you should probably remove it and try to degrease and dry it thoroughly. A warm (not hot) oven would help any remaining moisture to be dried out. Alterately, you could drown the chain with a healthy spray of WD40, which is designed to displace moisture. After the WD40, be sure to treat the chain with some real lubricant, as WD40 is not an effective chain lube.

30 seconds isn't bad. It takes a fair bit of hydraulic force to push grease out of a modern bearing assembly. If it's a metal bike, it probably has holes drilled in it to allow gas to escape during the welding process. These holes also allow water to enter/escape, so any water in the frame tubing has probably dripped out by now. That said, the BB area is a pretty good water trap, so pulling the seatpost and dumping whatever is in there is a good idea.

Well this weekend I made an unfortunate discovery. The Trek 820 I ride has a semi-cartridge bottom bracket. I apparently got enough water in there to make it rough. My LBS's advice was to ride it until it develops play and then replace with a cartridge bottom bracket.

I checked the spec sheet for my bike and found that all the bearings except the bottom bracket are sealed. Sure enough after submerging all the bearings (except the headset) the only one with a cold is the bb.

Why would trek make the lowest set of bearings on the bike (excluding the pedals) non-sealed? It seems like you could get away with a non-sealed headset, but if one of the main bearings is going to be submerged its going to be the bb.

But now I know. Luckily (I guess) I had bent a tooth on the middle chainring awhile back and so was thinking of replacing the crank anyway.

Also found recently though that the NOAA (http://www.weather.gov/ahps/) has a map of the US with the flood gauge readings of major rivers. Pretty neat stuff. Now I can check my route in the morning and see if I should stick to the high road.

Too many MUPs/bike paths are in places (like the flood plain) where nobody would put a road that people have to rely on to get places. I bet there is some good slick mud there when the river goes back down.

Best way I know to wash your socks!