The politician has been praised for his actions by police on New Year's Day.
Walker was walking with his fiancee Penny Tipu on New Year's Day when they came across a man who was standing on a six-inch wide ledge at the top of the Lake Hawea dam.
Tipu called police while her 33-year-old fiance skirted down the side of a grassy slope to where the distressed man was standing and managed to talk him down from the ledge.
Detective Senior Sergeant Malcolm Inglis was quick to sing his praise, saying he did a great job in helping the man to safety.
He 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.
"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 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.
He 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, the MP for Clutha-Southland, did not want to comment on the incident saying he was trying to stay focused ahead of his big day today.
Walker and Tipu have been together for three years after first meeting on dating app Tinder.
"She swiped right to me and I swiped right to her, and the rest is history," Walker told the Weekend Herald.
"On the first day we met up in a cafe and I bought a coffee before she arrived, being a gentleman from the deep south, and she drank the coffee.
"I bought her two more coffees throughout the date, and three weeks later I found out she didn't actually drink coffee ... she's incredibly polite."
He proposed to her in a paddock in Gore on Valentine's Day last year.
"Penny was cooking dinner and I tried to coax her out to one of our paddocks with a nice view, but she said she was busy.
"So I concocted a story about a couple of loose sheep on the road, and we had better get them off the road because there's clearly a safety issue ... managed to coax her out that way and proposed in one of our paddocks."
Walker said she had not expected a proposal, and was taken aback when he dropped to one knee.
The 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 he will be wearing a kilt as he watches Tipu, who is 28 and Maori, walk down the aisle to a chorus of bagpipes.
Tipu, a clinical psychologist, often jokes with Walker that she beat him to Parliament because she was former National MP Eric Roy's Youth MP.
They met before Walker became an MP in 2017, and he paid tribute to her in his maiden speech: "Penny, you're an inspiration to me and words cannot express how much your support for me."
Walker said they were planning to spend their honeymoon in a "quiet part of New Zealand".
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
