Darryl Fitch, 43, from nearby Paisley, is said to have been murdered in a violent assault. His body was found in the water at 19:45 on Monday.
It is believed that Mr Fitch had been camping or fishing with a 37-year-old male friend in the area since Friday.
Mr Fitch's friend is currently being treated in hospital.
Det Ch Insp Gary Boyd, who is leading the inquiry, said it was not yet known whether the death of Mr Fitch and the injury to his companion were connected.
He added: "I need the public's help to build up a picture of Mr Fitch's movements between Friday 10 July and Monday 13 July. Who he was with, who he met.
"I also need help from any of the local community or passing visitors to Locher Water between Friday and Monday.
"The area is popular with joggers, cyclists and families enjoying the water and surrounding pathways and I am appealing to anyone who was in that area between those dates to come forward."
Forensic officers have been searching the area and CCTV is also being checked.
The detective said he was particularly keen to hear from anyone who was in the area camping or fishing, or who knows of anyone who may have been, between Friday and Monday.
He added: "We have an incident room established at Govan Police Station and an incident caravan positioned near to the point where Mr Fitch was found. Officers are also in and around that area."
The camping companion of a man whose body was recovered from Locher Water in Bridge of Weir also suffered an injury, police have revealed.