2000 XL Passenger Floor Wet after wash

I have a 2000 Yukon XL that the Passenger Floor gets extremely Soaked after I wash it. The top of the Floor Mat doesn't seem to get wet, it but if I lift it up the carpet is drenched. I can almost hear the water pouring in but can't seem to find where its coming from. There is a Plastic channel or box of some sort in the dash just above the passengers feet, this seems to fill up with water and drain down the cabin side of the firewall onto the Floor.. HELP!!!!!.. I would appreciate any suggestions with this one.. Thanks!....jp

pull the kick panel and clean the lower hole out where the retainer presses in through the bottom of the car. this drain is clogged that drains the hood and fender gaps.