Residents around Whanganui’s Mannington Rd want council to address ongoing flooding issues

Residents say water can't pass through the Mannington Rd causeway, which has resulted in a closed catchment. Photo / Bevan Conley

Property owners on and around Mannington Rd at Ōtamatea are pleading with the Whanganui District Council to fix worsening flooding issues in their area.

A group of residents, including GirlGuiding New Zealand’s Whanganui representatives, presented their concerns at a recent council meeting.

They say the Mannington Rd causeway, constructed in 1988, was built with no provision to allow water to pass through it.

That had created a closed catchment.

Now, after a significant period of rain, the water level rose at least one metre within 24 hours, something that never happened when some residents bought their homes in the early 2000s.

Parts of properties were now permanently flooded, and that meant the water level would rise even higher in the event of heavy rain.

Flooding knocked out a resident’s underground power boxes in 2015, leaving them without electricity for four days.

According to the residents, a drain under nearby Pickwick Rd appeared to be flowing “unabated” into the catchment at a rate of around 120 cubic metres per day.

Other contributing factors were Waka Kotahi New Zealand Transport Agency putting in a concrete kerb and channel along State Highway 3 from Mannington Rd towards Pickwick Rd and ongoing housing developments on Pickwick Rd itself, with water run-off from both ending up in the closed catchment.

Girl Guides has been operating at its Great North Rd site since 1965.

The property runs behind Mannington Rd up to Kingston Way and is home to the Pickwick Carver Cottage.

Property manager Mariana Dowman said the field, which was used for camping, training and other activities, was now out of action.

Flooding on the Girl Guides' property in 2022.

“A little stream that sometimes had no water in it has turned into a great big lake. It’s overgrown, the grass is getting high and the girls can’t go down there,” she said.

“We have been to the council before, and all they could tell us was that the water table had risen.

“Now, a lot of other people are getting affected. I feel so sorry for them. It’s just ridiculous, and it’s spreading.”

Reports supporting the residents’ position from experts, including a hydrologist and an engineering surveyor, were presented to council members.

Whanganui Mayor Andrew Tripe told the Chronicle he and council chief executive David Langford had visited the area and talked to the residents.

Langford was now preparing a report to present to the council, Tripe said.

“This is a long-standing issue and it’s something that hasn’t been resolved easily.

“We need to work out how it’s happened and where [water] is coming from.

“Even when it’s not raining, there is water coming into the system there and it doesn’t have a pathway out.”

Tripe said no one knew exactly where the water pumping out of the drain under Pickwick Rd was coming from.

“I’m not an expert in this area, so I’m not one to talk about it technically.

“At the end of the day, we are about doing the right thing by our community wherever we can.”

People renting Pickwick Cottage had to be warned about the lake and the quality of its water, Dowman said.

“We recently had a group stay for a basketball tournament - a full house of 20-something boys.

“I had tell them, ‘Please, you are not to go down the bottom where the lake is’.

“This isn’t a normal lake. It’s just appeared. That’s the same with the people next door - they’ve never had a lake before either.”