Water leak

Hi, I have a 1973 dart swinger and I have a leak at the windshield. It is not the windshield leaking nor is it the wiper pivots. Whenever it rains, I have a lot of water in both front foot wells. I was told it was the cowl drainage vents are plugged with crap.
Has anyone encountered this and how do you get at the drains without taking off the fenders?
Thanks
John