The Reweti whānau home during flooding in 2015. Photo / Supplied
Whanganui’s mayor says he doesn’t have answers as to why a report 20 years ago recommending flood prevention work at the papakāinga of Pūtiki was never actioned.
In 2004, a Catchment Management Study on the Ngatarua Catchment commissioned by Whanganui District Council made a raft of recommendations to address known flooding issues at the riverside marae settlement in Whanganui.
Residents on Pūtiki Drive, who have experienced four severe floods in the past 20 years, are asking why they have been left to flood repeatedly despite previous councils being well aware of the risks and how to mitigate the issues.
Asked why none of the recommended actions had been taken, the district’s new mayor Andrew Tripe said: “I can’t answer that”.
He said it was “a long-standing and complex matter” but the new council would address the issue.
“Sometimes with this level of complexity, there is an avoidance of progress.
“We will focus on doing the right thing by those people affected.”
Tripe was elected to his first term in October.
“I’ve come up to speed with many issues and opportunities in a short time. I think people will give me a little leeway if I haven’t yet acted on this.
“There are three main stakeholders at play here: Horizons Regional Council, Whanganui District Council and Waka Kotahi, making this a complex situation.
“Where there are three stakeholders all with a role to play to address an issue, that’s when it gets complicated and a bit of apathy sneaks in.”
Tripe said he had spoken to Whanganui District Council chief executive David Langford to agree on the next steps.
“Talk is one thing and action is another. People are starting to see that we are a council that will act and get stuff done.
“We are committed to understanding where the roles and responsibilities sit and to have agreement upfront about how things should progress from here. We will act appropriately.
“We need to make sure Horizons and Waka Kotahi also come to the party. It needs all three to co-ordinate and act so there is a whole solution, not just a bit part.”
Lisa Reweti, who lives with her parents Simon and Carolin in Pūtiki Drive, said their home had been flooded repeatedly, as had the neighbouring kaumātua flats and other homes, forcing late-night evacuations, including carrying kaumātua to safety.
Reweti said she was passed “from one to the other” while trying to get the three entities to take action.
She said the Ngatarua stream was diverted in 1962 to build the state highway connecting to the new Cobham Bridge and should be returned to its natural path. Culverts should be bigger and the road height reduced so it doesn’t trap floodwater on lower-lying properties.
The Catchment Management Study by Opus in 2004 raised these as key issues. It said Pūtiki Drive in effect acts as “a retention dam” during heavy rain, with the modified stream unable to contain “all but the smallest rainfall events”.
The report says the culvert is too small and houses on Pūtiki Drive up to half a metre below the built-up level of the road “would suffer widespread flooding”.
“Flooding upstream of Pūtiki Drive is due in part to the culvert under the road limiting the volume of water that can pass [sic] downstream,” the report said. “Flooding downstream of Pūtiki Drive is in part due to the loss of an appropriate stream channel by modification.”
The report recommended increasing culvert sizes under roads and entranceways from Pūtiki Drive to the Whanganui River and reinstating “an appropriate” stream channel downstream of Pūtiki Drive.
Vegetation should be managed to improve stream flows and, as a minimum, some of the constraints in the stream channel should be removed to improve water flow and reduce upstream floodwater levels. A small bund was also recommended to prevent flooding to the north.
A further potential issue was the programmed discharge from 2005 of stormwater from an additional 14ha of residential properties on the southern side of Durie Hill to the Pūtiki Drive culvert inlet.
Building a flood retention dam would reduce flooding both upstream and downstream of Pūtiki Drive and mitigate the effect of the higher peak discharges of stormwater from Durie Hill, the report said.
The work was estimated in 2004 to cost up to $178,000.
Tripe said he visited the Reweti whānau informally about two weeks ago.
“I introduced myself [in an effort] to literally get the lay of the land, the issues, some background for my own understanding and their perspective on a long-standing and complex matter.”
Tripe said Pūtiki was at risk of flooding not just from the stream but from all sides, including the hills and the Whanganui River, and the land might not be deemed appropriate for building if assessed under today’s regulations for building and zoning.
Asked if the council owed an apology to the Pūtiki community, Tripe said he would apologise if appropriate, once he had a clear understanding of the issues, where the roles and responsibilities of the Whanganui council, Horizons and Waka Kotahi sat, and how to move forward.
Asked if there would be compensation for flood victims, Tripe said he would “not entertain” the question until he knew more about the situation.
“Weather events are happening all around New Zealand. There’s a point at which Mother Nature has to take the blame.”
Asked if the council could use some of its nearly $24m Better-Off Funding, widely described as a Government sweetener for Three Waters reforms, to urgently do the work required, Tripe said he understood the money had already been allocated.
“A lot of fixes are required around our district. I’m thankful that our Three Waters in general have been well invested in. Notwithstanding that, there are issues like this one and others in our town and in the rural areas.”
He said managed retreat had not been discussed.
“It is very early days in my term. [The Pūtiki situation] is one of many things on the list and we’re committed to acting.
“One of my strengths is facing into complex issues and acting on them. This one, in the scale of things, only affects a small number of our community – but that doesn’t matter. It needs to be addressed.”
Horizons Regional Council group manager of catchment operations Dr Jon Roygard said the regional council had been alerted to flooding issues at the Reweti property in the past.
“[We have] visited the site in conjunction with Whanganui District Council and Waka Kotahi to determine what’s causing the issue.
“The flooding is a result of high flows in the Ngatarua Stream reaching a culvert adjacent to the property on SH4 that doesn’t have capacity to handle the flow, meaning the stream backs up and floods the property.”
But Roygard said the issue was Whanganui District Council’s to deal with.
“While we have empathy with the situation that Lisa Reweti’s parents are in, this stream is part of Whanganui District Council’s urban drainage network and not part of a Horizons’ flood protection scheme.
“We are working with Whanganui District Council on improving flood resilience in Whanganui and are happy to provide technical advice to them to assist with this issue.”
Roygard said the regional council’s future work programme includes design work for flood protection in the Pūtiki area downstream of the area in question. He said the work may assist by increasing capacity in the Ngatarua Stream.
“This project will require a range of consultation and design work that is planned to start later in the year.”
Waka Kōtahi said yesterday a potential long-term solution would require a multi-agency approach in partnership with local territorial authorities.
A decision on whether the current culvert needs upgrading to a larger size was expected by the end of the month. In the meantime, the culvert would be cleared regularly, the agency said.
Under the Government’s Local Water Done Well reforms, all councils must submit a plan.