"We saw the lambs were swimming in the water and the ewes were standing in quite deep water.
"They were paddling the water ... the lambs would have drowned," he said.
All four got in to help. Driving rain didn't deter them.
"We stripped down and jumped in and lifted them over the fence and put them on higher ground."
However, two lambs just lay on the ground exhausted, so they took them to a neighbouring farm, Mr Harrison said.
"They knew who they belonged to and put them somewhere safe."
He said he didn't think twice about rescuing the lambs and believed his compassion for animals came from his mother, who once owned a pet shop in Wainuiomata.
"It's just what you do," he said.
The group had to turn back to Masterton after the rescue because the road was flooded.