During a break in the storm on Sunday they tried to cross back to Hoods Landing, but the boat capsized, throwing the men into the river.
His friends were found clinging to trees and were saved, but Mr Singh's body was recovered from further up the river.
Mrs Singh said her husband came to New Zealand as a teenager with just $20 and a scholarship to the University of Auckland, where he studied law and went on to become one of country's most well-known immigration lawyers.
Their Mt Eden firm, Shean Singh Barristers and Solicitors, specialises in immigration and commercial law and was founded after Mr Singh worked for top firms, including Simpson Grierson.
He was the first Indian lawyer to go to the Supreme Court, in 2005, where he was successful, and was instrumental in the establishment of the New Zealand Immigration Advisers Authority.
"He's a self-made man and very disciplined in his own way, I really admire him and am so lucky that I married him.
"He built a castle for me, he proposed to me under a kauri tree and he said, 'I will build a place where you can see the tree every morning when you wake up', and now I can see the tree from my bedroom.
"Then he built a treehouse for the children in the tree. It was like a Cinderella dream come true."
She said her husband had a strong work-life balance, starting work at 6am each day and finishing at 3pm to spend time with friends and family, and was known for his sense of humour. Tributes had been made to the family from all over the world.
A funeral for Mr Singh will be held at North Shore Memorial Park in Albany at 1pm today, and prayers will commence at 9am on Friday, June 5 and continue until June 7 at the Gurudwara Sahib temple in Takanini.
Mr Singh's death was among a number of others this duck hunting season, with 15-year-old James Johnston, from Whakatane, and 21-year-old Josh Hill fatally shot in separate incidents on May 11.