Tauranga City Council is making Plan Change 27 – Flooding from Intense Rainfall operative after three years of legal wrangling.

The plan change has had legal effect since 2020, when it was notified for public consultation.

It introduced rules to manage flood risks and the effects of flooding on people, properties and infrastructure. These impacted what could be built on land deemed a flood risk.

The council also released new flood hazard maps for the city based on a one-in-100-year storm scenario and accounting for climate change forecasts.

The maps deemed 30,400 properties at risk of flooding - thousands more than under the previous modelling.

An independent hearing panel heard submissions on the plan change and the decision to approve it was notified in April 2022.

Twenty parties took three appeals to the Environment Court. The cases were settled in mediation, avoiding a hearing.

Tauranga‘s Urban Task Force (UTF), which represents property owners, developers and businesses, was one appellant.

The UTF cited significant errors and inaccuracies, claiming the maps did not show the most up-to-date flooding information.

The task force also believed the plan change would hurt property values across the city.

Through the court process, the council agreed to keep the flood maps updated so they could be relied upon by developers and landowners.

UTF chairman Scott Adams, managing director of development company Carrus, said all parties generally accepted there were technical errors and issues with the mapping.

“[The] council has accepted through the appeal that a site-specific technical assessment on flooding will now prevail over the indicative maps that are currently shown on the council’s online GIS [mapping tool] layer.”

“This is a significant win for the UTF on behalf of property developers and landowners,” Adams said in a statement.

“They can now get a simple stormwater engineering assessment to override the mapping. This will be particularly useful where there are errors with the flood modelling and map outputs.”

The council also agreed that whenever its stormwater model was updated using more up-to-date or site-specific information, this would prevail over the indicative flood hazard areas depicted in its GIS layer.

Other concerns raised by UTF about how roadworks might affect flooding were also addressed in the new consent provisions issued by the Environment Court.

Adams said roads were designed to help carry stormwater during major floods.

UTF’s concern was if the council improved roads – like raising the height or adding engineering features – it could cause floodwater to spill onto nearby properties or reduce the ability of stormwater to flow along the roads, he said.

Because of this, Plan Change 27 was altered and neighbours must now be notified if roadworks could cause flooding on their properties.

Policies have also been updated to focus on reducing flood risks, rather than just managing activities. The goal was to ensure that activity still maintained suitable overland flows that water takes during floods, instead of restricting the activities themselves.

The Environment Court consent order was signed off by Judge Kelvin Reid in March.

The council approved the plan change at a meeting last week. It would become operative on May 13.

City planning team leader Janine Speedy said the process started after Tauranga had significant flooding events in 2005, 2010, 2011 and 2013.

The council then looked at how it could better manage risk from flooding, Speedy told the meeting.

An integrated stormwater project was started, and Plan Change 27 was the regulatory response for this, Speedy said.

Prior to 2020, the council didn’t have any flooding rules in the City Plan and Plan Change 27 introduced those rules, she said.

The council had an ongoing flood modelling programme to ensure its information was up to date, Speedy said.

Councillor Glen Crowther said it was helpful to have the issues dealt with through the legal process.

It was important to get it right and there was a lot of effort put into it to ensure that happened, he said.

LDR is local body journalism co-funded by RNZ and NZ On Air.