Wairoa District Council is looking for answers to explain the unusual flooding during Cyclone Gabrielle.

It's launched an independent investigation to understand whether the flooding was linked to heavy amounts of slash.

Mayor Craig Little has suggested there was a theory Genesis opened the Waikaremoana Dam floodgates - which Genesis denies.

He says the river was uncharacteristically different from its normal flooding.

"Bridges were blocked up like beaver dams, rivers went different ways out in different places. One part of the town was flooding, another part hadn't quite started flooding, which was very unusual."

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