After a trek to the back of the lake and behind the dam, I decided to use the "Return To Home" function on the Phantom 4.
Shortly afterward, the drone appeared to struggle to lock on the the home point ( maybe the high wind and water scrambled it's barometer readings or GPS signal somehow ? ) and started to drift over.
At this point, deciding to cancel the" Return To Home" command and bring it back home manually, it preceded to land anyway ( on the water and not the home point ). Fortunately, using full throttle and some pitch, I kept it aloft long enough to get it to dry land.