Water Leak

Water leak in passenger front floor at front right corner of floor. Did everything I could think of to find leak. Started at bottom of windshield and worked down, leaking all the way. Removed exterior 'A' pillar cover to check seal around clips- all OK. Then removed cowl cover and reservoir tank, started low and worked up, leaking all the way. Determined the leak was originating inside the fender (Oh! Happy days!) After much experimentation found a vertical to horizontal lap of two metals about three inches behind the top hinge. Looked like a blister between the metals. Purposely ran small stream of water directly into this seam. BINGO, leak. Dried area and forced caulk in between this seam and another just a little higher. Checked the next day and NO leak.
Hope this is helpful to someone else.