Walker, who is marrying Tipu tomorrow, did not want to comment on the incident saying he was trying to stay focused on his big day.
However, Detective Senior Sergeant Malcolm Inglis confirmed Walker had brought the 28-year-old man down from the ledge, which is about 10m above the churning water.
"He was heading up to have a walk with his partner when he saw a man in distress. He talked him into coming away from the edge of the dam. He was there, on the spot, and did a very good job."
"He calmed the situation down and then went back with police to the Wanaka police station, and waited with police until medical assistance arrived.
Inglis said it was important to try engage with people in this kind of situation, rather than turning away or being afraid of saying the wrong thing.
"To engage can be quite frightening for people in those situations, because they're not sure what's going to happen. It was fortunate he came along and made the effort to stop and see what was happening.
"He's done a really good civic job of taking the time to engage, and talk him into coming with him and away from a dangerous situation, and then buying him some smokes and food to calm him down."
Inglis said the result would have been "very nasty" if the man had not been talked down.
He said in general people sometimes had demons to fight after a night of New Year's revelry.
"It quite often happens on New Year's day after a night out of drinking. It's not unusual to get depressed, or have relationship problems."
He said there had been speculation that Walker had been arrested after he was seen getting into a police car.
"But he was actually doing a very good deed."
Walker and Tipu's wedding will be held at special events centre The Port Molyneux School at Kaka Point just south of Balclutha, with about 120 guests including 15 National Party MPs.
Walker's family has strong roots in Balclutha, but his heritage is Scottish and Walker, 33, will be wearing a kilt as he watches Tipu, who is 28 and Maori, walk down the aisle to a chorus of bagpipes.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• LIFELINE: 0800 543 354 (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757