The level of the water was up to the middle of the headlights, or the resulting wave?

I took mine through some muddy water (not quite as deep as yours) and my oil light came on for about 10 minutes. Then it slowly faded away and nothing seemed wrong when I checked it later that day at home.

My horn got messed up too. Got some water in it and everytime I used it, it sounded like a drowning cow. I replaced it at Kragen's. Don't remember the exact price but it was around 10 bucks if not cheaper. This could be your chance to upgrade to a horn that's actually stronger than a Civic's.