"This one came so quick, so fast, it's done a bit of damage to the fencing and drains.
He said the weekend's rainstorm sent a torrent of water through the farm, submerging nearly a third at a time when "every inch is needed for grass".
"The flood water came right down through the cow shed and parts of the farm would have been about a metre deep, running quite strong, swift water coming down.
"At the peak we had about 50 hectares under. It's starting to drop now but looks like we'll have to regrass at least 30 hectares because it's going to be there too long," Smeath said.
"I've been here long enough now and we've been through a few of these. It works out about $1500 a hectare for every hectare you have to regrass."
Hikurangi Swamp was one of the largest wetlands in the southern hemisphere before a drainage scheme was built. Smeath said the farm is not insured against flooding due to the expense of insuring floodprone land.
"It's still $40,000 and takes the icing off the cake I can ensure you."
Authorities do not yet know how many people have had to move out of their homes in Northland due to flooding. EQC has so far received 117 land claims for the Northland flood, but this does not record displacement.
"I've been through these sort of things before and we'll come right. The biggest thing is keeping your focus and having a plan going ahead," Smeath said.
"I'm at that age and stage where I could probably go and sell up tomorrow and be quite comfortable but I enjoy farming and cows and so I'll probably keep going for a bit longer."
- RNZ