This year, water filled my axle resivor

Today when I checked the level on my axle ail, water just poored out for 5 or more mintues. How is water getting in here. I had it changed when I bought it at the Ofallen Mo Bob Cat dealer.
I read about a top inspection plate. I think thats at my feet. I would think, the dealer put it on with a seal to keep water out, maybe they did not do this.

This year, water filled my axle resivor