They also found a set of footprints leading into the water where the main river flow goes into the lake.
The search continued with an extensive aerial and shoreline search this morning, but no further signs of Mr Copland were found. A boat with sonar equipment was deployed, focusing its search at the rivermouth where it meets Lake Wanaka.
Police said it was likely that Mr Copland had waded into the water and onto a terrace off the gravel island that boarders the main river flow and the head of the lake.
"All indications are that he has slipped off the edge of the terrace and into the flow of the river and into the head of the lake,'' senior constable Mike Johnston said earlier today.
Police said tonight that they expressed their sympathies to Mr Copland's family and thanked LandSAR, the Wanaka Coastguard and local volunteers for their efforts in searching for him.
Police have now referred the matter to the coroner.