The Piako River is at risk of overflowing after the Hauraki Plains has in the last few days been saturated with the same amount of rainfall as fell during recent cyclones.
The Waikato Regional Council is keeping a close eye on the river's water levels, which are higher than normal, and is warning local farmers and duck shooters in the Kopuatai Peat Dome area of the overflow risk.
After Cyclones Debbie and Cook the river over-topped its stopbanks, causing extensive surface flooding. The banks over-topped as designed when the river is in flood.
However, the council says it expects its flood management system to cope with the recent downpours.
Regional hazards team leader Rick Liefting said it was unlikely any overflows would be significant or cause more surface flooding in emergency ponding areas like paddocks this time.
However people in the area needed to be aware that the water level was high and rising and could potentially overtop slightly, Liefting said.
Duck shooters in particular should be careful, he said.
"The catchments continue to be very saturated in the region. Any surface water from this latest rainfall in the Piako catchment will take time to move into the drainage systems, helping keep waterway levels high."
Flood response staff would continue to monitor the situation, Liefting said.
"But, with no more rain forecast for several days, we do not expect any major spilling to ponding zones even though water levels will remain very high for some time for the Piako."