Lower North Island and Marlborough
Between 14 and 17 February 2004, intense rain (up to 300 millimetres in two days) fell on land already saturated from previous severe weather. Worst affected were rivers in the South Taranaki, Manawatū–Wanganui, Wellington and Marlborough areas. The Manawatū River peaked at its second-highest level on record. Many rivers breached their banks, spilling silt-laden flood water through towns and across farmland. A number of rural communities had to be evacuated, and at the height of the emergency about 2,300 people had to leave their homes and farms.
About half the roads in the Manawatū–Wanganui region were closed and more than 20 bridges were damaged. The civil defence operation was the largest in 20 years, with air force helicopters rescuing stranded people and dropping supplies to communities cut off by flood waters.
In Marlborough, in the upper South Island, the Waitohi River flooded into Picton, and 500 people were evacuated for fear an overflowing water supply dam might collapse.
The February floods cost over $112 million in insurance payouts, and the government granted $135 million in aid to farmers. Around 2,600 farmers were affected by the flooding, with some having to abandon farming their properties. The total economic impact was estimated to be about $400 million.
Eastern Bay of Plenty
In July 2004, the eastern Bay of Plenty was extensively flooded when a frontal system stalled over the area, causing prolonged and intense rain. The Whakatāne River spilled into Whakatāne’s central business district and the Awatapu area. Water had to be released into the Rangitāiki River from the Matahina Dam to prevent the dam from bursting. The Rangitāiki overflowed above Edgecumbe, creating a 100-metre-wide breach in its stopbanks. Flood waters entered Te Teko and Edgecumbe, and swamped some 17,000 hectares of farmland.
At the height of the floods, about 3,200 people had to leave their homes, many sheltering in evacuation centres and on local marae. A swarm of shallow earthquakes north-east of Rotorua added to the misery, triggering many landslides on saturated hillsides. In all, more than 450 farms were affected by the floods, with over 200 homes made uninhabitable.