Warning lights

[Ingo Rautenberg]

Most likely (OK, definitely), you got water into the alternator and it
stopped charging (funny how those alternators don't like the water, yet are
placed so low on these cars).

Of course, your belt is also likely loose, and that coupled with the wet
alternator made charging even more difficult.  I'd check the belt tension
and just keep an eye on things for a while.

-Ingo
'91 200q20v...Slightly modified  + '83 Urquattro
http://hometown.aol.com/quattringo/index.html