Oh, I get it now. Actually, rain drainage is the reason for which I didn't position the waterfall in the bottom corner in my little montage (as there are water drainage marks on the lawn in this corner), but I didn't think about more water drainage being stopped by the waterfall stones. Hence your point to locate it on the other side, I get it now. Hm. It would seem tricky to try to redirect drainage water to the driveway, the terrain actually goes up gradually towards the driveway (can't take a pic now, there is snow on the ground, this wouldn't show much). Given the shape of the street (going down towards the bottom part of my satellite pic above), the presence of storm drains and the fact that excess water does seem concentrated in the bottom corner, I don't know if the issue would be that significant though. Maybe simply locating the waterfall at the top as you suggested (and the skimmer at the other end, near the seating area) would be good enough? Let me add this topic to the list "to discuss with contractor" though. Thanks again for the great inputs, appreciated.
This was my first thought after reading Steve's post, but I had no idea if this would be realistic! Sounds that it might be?