A spring surging beneath an airfield in Swannanoa is one of the headaches facing the new Waimakariri district flooding response team.
Some of the area's newest and most expensive homes and sections have been flooded in the past fortnight, following one of the heaviest sustained spells of rain since the 1970s.
A focus for the council has been the corner of Tram Rd and No 10 Rd, where an undercurrent - a flow of water beneath the ground - ran into down-country properties for the first time landowner Des Lines could remember.
He and wife Adrienne remember their children messing about in the occasional current in the early 1980s. Not long after they bought the property, they learned there used to be a well on the spot where their house is now.
However, the water never flowed like it had since a storm a fortnight ago.
Lines, a former commercial pilot, has a private airfield which has been unusable since an undercurrent sprang up.
He considered building a bund to channel the water but was worried about the effect on neighbouring properties.
The Waimakariri District Council is also considering its options in Mandeville and low-lying pockets around Kaiapoi and Rangiora.
It has had to defend its housing policy, with flooding hitting the two towns, as well as Fernside and rural residential plots at Mandeville, where some residents could be forced to use portable toilets for months.
Septic tanks on about 50 properties were affected by the flooding and 23 portable toilets had since been distributed.
Mayor David Ayers acknowledged the low-lying southwestern side of Kaiapoi had always been prone to flooding, but earthquake damage had made it harder to fix trouble spots.
There could be "some significant costs involved" in finding lasting solutions, especially in Island Rd, bordering Silverstream, but also in the town in Wesley and Otaki streets.
There had also been quake damage in the northeast, around Bracebridge St and Feldwick Dr, where some land had slumped by 300 millimetres.
Weather had been the biggest factor in the recent flooding, Ayers said.
Some of the rainfall in the past couple of months had not been seen since the 1970s.
In April, Kaiapoi received five times its monthly average. This followed three times the monthly average in March.
It was wrong to blame the flooding on new housing or rising water tables from farm irrigation, Ayers said.
"We've got a lot of low-lying land in our district and that's just geography. It's been the wettest period we've seen since the 1970s in the eastern half of the district, so we are living in pretty extreme conditions."
- The Press