John Maulder on the bank of the Titoki Wetland. Photo / Bevan Conley
Whanganui District Council’s chief executive says a Castlecliff resident’s demands to lower the water level at Titoki Wetland are unlikely to be met.
However, the council will look into flooding issues affecting the suburb.
John Maulder has spent the past eight years complaining to the council about excessive surface water in his area, an issue that began for him around 2011/12.
Maulder, who has lived at the same property on Polson St for 40 years, says insufficient stormwater infrastructure, the natural flatness of Castlecliff and the industrial developments on nearby Mill Rd are exacerbating the problem.
“For me, it started off with a puddle in the driveway, which you don’t worry about, but the following year that puddle got bigger,” he said.
“Then, it got to the point where you’re thinking ‘What the hell is going on?’ Sometimes we were getting flooded twice a year.
“If there is water hanging around on the front lawn then it’s the same underneath the house. How long does that take to dry out?”
Following the major flooding event in Whanganui in 2015, Maulder presented a petition signed by 70 Castlecliff residents to the council.
It asked for the Titoki Wetland to be lowered by 1.5 metres - back to its “original level”.
Maulder says the council backfilled the wetland in 1986 - although the council has no record of this - causing the water table to rise and the area to flood more easily.
Backfilling is the refilling of an area created by digging or drilling.
The petition prompted an interim council report.
It said that land use had drastically changed over the last few decades and deforestation in the catchment area “may very well have contributed to the conditions observed by the petitioners”.
The council didn’t formally provide a groundwater level of service, but it had no objections to people making on-site improvements and connecting to the stormwater system, as long as the connections were compliant with installation standards, it said.
Any improvements would be at the property owners’ own cost.
Council chief executive David Langford met with Maulder earlier this year.
He said Maulder was passionate about the area he lived in and wanted to see problems fixed.
“That’s a good thing, actually.
“I’ve agreed we’ll do a bit of research around what we can do to relieve the flooding issues but there is no guarantee that will result in a project that will do what John wants us to do.”
The best-case scenario for Maulder would be the council putting a business case together for the project, Langford said.
“Council would approve it and put some budget aside to get it done.
“But, based on the fact that council has already considered this matter and voted against it, and there are some pretty big regulatory hurdles in terms of getting consents, that outcome still doesn’t look likely.”
Titoki is a Category A wetland under Horizons Regional Council’s One Plan.
Robert Hill has lived on Titoki St since 1969, owning multiple sections next to the wetland since then.
He said he watched council workers carry out backfilling work at the site.
The council’s senior stormwater engineer, Kritzo Venter, said they could not find specific evidence of the backfilling after searching the council’s work history and documented files from that period.
“We are, however, aware of similar anecdotal statements having been made by others,” he said.
Venter said when comparing historic aerial pictures from the period before the alleged backfilling, it appeared there may have been a wider wetland-type landscape surrounding the current wetland.
“The land use has been changed to grazing, as is currently the case, so we assume the change must have happened around this time.”
There was no data available to make an “evidence-based assessment” on whether the backfilling would have affected Castlecliff’s water table, Venter said.
Maulder said digging out the drainage ditch that ran along the wetland to Rogers St would fix the problem and “wouldn’t take more than a day”.
Surface water problems were now affecting Polson, Titoki, Thatcher, Lee, and Manuka Sts, he said.
In 2021, Maulder filed a complaint about the council’s handling of his wetland complaints to the Ombudsman.
According to Chief Ombudsman Peter Boshier, the Resource Management Act (RMA) identified wetlands as a matter of national importance and provided for their preservation.
“In recent times wetland protection has been strengthened by the National Policy Statement for Freshwater Management and the National Environmental Standards for Freshwater. Regulation 53 of the National Environmental Standards specifically prohibits the draining of a wetland.
“On this basis alone, the Council’s decision to not lower the water level of the wetland does not appear unreasonable.”
Boshier said it was hard to see on what grounds the council could be criticised in handling Maulder’s concerns.
“Your complaint is based on the claim that the earthworks in the Titoki Wetlands raised the groundwater level of the wetlands and the neighbouring Castlecliff. The alleged result of this is that, when there is excessive rainfall, certain properties in Castlecliff flood.
“The council’s position, as stated, is that there is no evidence to support your claim.
“At this stage, it is difficult to contradict this. You have not provided any evidence to counter the Council’s claim. Without compelling evidence, it would be difficult for the Ombudsman to say that the council’s position is unreasonable.”
Venter said there was a plan to build additional wet-weather storage adjacent to the wetland for future development from the Fitzherbert Ave area in Springvale.
The stormwater plan for the nearby Mill Rd industrial area was on schedule, “relative to the pace of current developments”.
A new stormwater main had been laid along Mill Rd from the intersection with Manuka St, which discharged to an open watercourse on the corner of Mill Rd and Mosston Rd, Venter said.
“From here there are two discharges.
“Primarily it flows under a culvert to the Titoki Wetland, from where it enters an underground pipeline along Titoki St, down Rogers St.
“It then discharges to another open watercourse by Matipo St - adjacent to the Kokohuia Wetland area - after which it finally enters a larger pipe on Rogers St to discharge to the Whanganui River.”
A pipeline recently built down Mosston Rd to Wharf St would act as a second discharge.
“It will act as an overflow structure to divert flows from the future attenuation area on Mosston/Mill Rds away from the Titoki Wetland and downstream catchment,” Venter said.
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