The work has been undertaken through the joint Dunedin City Council and Otago Regional Council South Dunedin Future programme, and will be presented to councils on 24 and 25 June respectively.

South Dunedin Future Programme Manager Jonathan Rowe says the analysis provides a more comprehensive picture of what it would take to manage flooding in one of Dunedin’s most complex and exposed urban environments.

“The encouraging finding is that, even as flood hazards increase, it is feasible to significantly reduce risk – potentially to levels comparable to, or lower than, today,” Mr Rowe said. “However, achieving that outcome would require sustained effort over many decades, including major investment, disruption, and change.”

To help guide discussions about how South Dunedin might adapt over time, councils have developed three proposed adaptation futures. These are options only at this stage - no decisions have been made. Community consultation and further technical work will take place before a final masterplan for South Dunedin is presented to Council.

The Futures build on previous work and reflect community feedback during earlier stages of the South Dunedin Future programme. Each outlines a different approach to managing flood risk through combinations of infrastructure investment, land use change, and urban development.

The futures span the short (2025-50), medium (2050-75), and long term (2075-2125) timeframes.

Reducing flood risk at this scale would require:

• Upgrading stormwater and groundwater infrastructure
• Creating new parks, wetlands, and waterways
• Raising land in some areas
• Potentially moving people and buildings from the highest-risk locations

Each future adopts a particular way of managing risk and comes with different trade-offs in terms of costs, disruption, and change.

• Future 3 – Protect (Keep the land dry – raise land and pump water) Seeks to keep the land dry through a focus on engineered systems — pipes and pumps — with some land raising, green space and coastal protection.
• Future 4 – Restore (Make space for water – waterways and wetlands) Seeks to make space for water, by reintroducing open waterways, wetlands, and other green spaces to complement the pipes and pumps.
• Future 5 – Reshape (Move out of harm’s way – raised land and green spaces) Seeks to move people out of harm’s way using land raising and infrastructure alongside new green spaces and waterways. Coastal protection is moved inland.

The futures are similar in the short term, focusing on infrastructure upgrades and preparing for potential land-use change. Larger changes would emerge over the medium term, including land raising, new development patterns, and expanded green and blue spaces. By the long term, major capital works reduce, while new housing in lower-risk areas supports future growth. “The proposed changes are significant, but they reflect the scale and nature of the challenges facing South Dunedin now, and in the future,” Mr Rowe said.

Mr Rowe emphasised that no decisions have been made. The three futures are proposals, intended to inform discussion and decision making rather than to predetermine outcomes.

The advice on the proposed futures will be considered by Councils on 24 and 25 June.

Any future decisions – including potential plan changes, rezoning, or infrastructure investment – would be made by Councillors, subject to further analysis, community input, and standard council processes.

As councils explore options to reduce flood risk in South Dunedin over the next 50–100 years, including the three proposed futures, it is likely that achieving meaningful risk reduction will require the purchase of private properties in some areas. This may be needed to support work such as new or upgraded infrastructure, raising land above flood levels, and creating green and blue spaces to store and move floodwater.

The three futures identify general areas where interventions such as new pumps and pipes, land raising, and parks, wetlands and waterways could be located. These areas are shown on maps and in visualisations, but are indicative at this stage, based on analysis to date.

“The locations shown in the technical reports are based on current information and are indicative only. Specific properties would be confirmed later, after detailed project design. Any final decisions would be made by Councils, after considering community feedback and further technical advice”, Mr Rowe said.

If property acquisition is required, this would follow established council processes and approvals, and be subject to available funding. The current intention is that any acquisition would be undertaken over time, on a voluntary basis where possible, at market value, and in accordance with relevant legislation.

Additional information about potential property acquisition will be made available on council websites and shared with the South Dunedin community.

While the futures are grounded in scientific, engineering, and economic analysis, councils are clear that the work necessarily relies on assumptions and simplified representations of complex social, environmental, and economic systems evolving over a century.

“There is uncertainty that cannot be removed,” Mr Rowe said. “Adaptation planning can help manage that uncertainty, for example by keeping options open, staging decisions, and avoiding lock-in, but it cannot eliminate it altogether.”

While acknowledging community frustration regarding the perceived lack of action on flooding since 2015, it has taken time to build a comprehensive understanding of the underlying problems and to identify workable long‑term solutions. This analysis confirms there are no quick or simple fixes and that system-scale responses are required.

This longer-term, system-wide work under South Dunedin Future is part of a broader package of flood-related investment. It complements current work to design and deliver three South Dunedin stormwater projects previously approved by DCC (valued at $29.2 million), as well as work to address wastewater overflows at Surrey Street.

The stormwater and groundwater modelling undertaken in this stage of work has supported more detailed economic assessments. These show the estimated costs of the three futures are less than previously predicted and less than continuing with a status quo approach (when factoring in the benefit of avoided flood and other damagers).

Costs for the three futures range from $1.63B to $2.45B in present day value over 100 years. For context, the cost of implementing the lowest cost future (Future 4) is roughly 8 per cent of DCC’s annual capital budget of around $200 million, noting South Dunedin comprises around 10 per cent of the city’s population. When accounting for the expected benefits of each future, in the form of avoiding loss and damages from flooding and coastal inundation, the net cost of the futures range from $280 million to $1.1 B.

This compares favorably to indicative costs of $2B to $7.1B for options considered in the previous stage of the programme and the overall cost of continuing the current approach under a status quo approach, which is estimated to be between $1.45B – over $2B.

The analysis also highlights that delayed or insufficient action would see flood impacts
continue and worsen over time.

People seeking additional information can visit DCC’s webpage

Subject to Council approvals, public engagement on the proposed adaptation futures runs from 1 July to 9 August 2026.

Council staff will also be available to speak with the community during public drop-in sessions and workshops, and feedback can be shared in-person or via an online survey.

“There is more work to do, and there will be many opportunities for the community to ask questions and provide feedback”, Mr Rowe said.