Hello all. 

I just noticed a coolant leak out of what appears to be a drain plug in the engine on the driver's side of my '87 westy. It's flat, about 1" across with a slot in it and sits just to the left and behind the oil drain plug. Anyway, I'm not sure if it's plugging the cooling system, but it appears that coolant is leaking out of there.  I suppose it could be the water pump as well, but it didn't appear to be dripping down from above. I'm planning on doing some driving this weekend and wanted to hear opinions on:

Is the big plug likely where it's leaking from?
Will this leak get worse?
What's the best way to fix it?

Thanks!
Aaron '87 Westfalia