Matahina Dam responsible for flooding, say residents
Edgecumbe residents are blaming the Matahina Dam for the flood that swamped their small town.
The criticism echoes a similar complaint made after the 2004 Edgecumbe floods.
Not enough water was released through the dam prior to the heavy rains, say some.
But the Bay of Plenty Regional Council say that management of the dam cannot be blamed.
Resident Graeme Bourk told RNZ he was less than 20 metres from the floodwall before it collapsed.
He said the dam should have been spilled for at least a month to avoid the flooding.
A similar event happened on the other side of Edgecumbe in 2004 and TrustPower, which operates the dam, said it would never happen again, Bourk says.
Colin Holmes, the former mayor of Whakatane, agreed with Bourk's comments and said TrustPower panicked and opened the dam too late.
"Exactly what happened in 2004. Poor information, poor flood management protocols between the regional council and Trustpower. Result: disaster," he told RNZ.
However, the Bay of Plenty Regional Council say the water was already at a minimum level before the flood.
"TrustPower started lowering the levels in Matahina Lake from Monday lunch time - well before the predicted rainfall," said flood manager Peter Blackwood.
"Council activated its Whakatane flood room at midday on Wednesday and [the experts] worked round the clock to minimise flood damage and protect communities.
"The flood management plan for the Matahina Dam is designed to take 100 m3/s off the flood peak," the release said.
"We exceeded this by taking off 110 cumecs per second. If we hadn't used the storage in Matahina dam, 12 per cent more water would have flowed down the river at the peak of the flood.
"Tough decisions were made well and our data shows that those have paid off."
Blackwood said river levels were at one in 500 year levels and the stopbanks are only designed for 1 in 100 year levels. "Ex-cyclone Debbie rainfall levels were very high. On the Rangitaiki, sites logged between 200-320mm in 48 hours," Blackwood said.
"Stop banks in the Eastern Bay are designed for a one-in-100 year event. At their peak, river flows were more than 30 per cent larger than this."
Council flood manager Roger Waugh, told RNZ that TrustPower did exactly what was asked of them.
TrustPower, at the orders of the council, started increasing flows on Monday and by Wednesday night, all spill calls were one.
The dam was still being re-filled on Friday.
The failure of the concrete section of stopbank in Edgecumbe "happened very, very quickly". It was not known why yet, but there was seepage underneath it, Waugh said.
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