Ōreti floodplain project
Environment Southland is undertaking a programme of flood bank and river management work in the lower Ōreti catchment. This work is known as the Ōreti Floodplain Project.
It supports communities including Winton and Dipton West, surrounding rural land and important regional infrastructure. Winton is a key service town on State Highway 6, providing healthcare, education and emergency services to the wider rural community.
By 2040–2050, the Ōreti catchment is expected to experience around 10 percent more rainfall and a 13 percent increase in river flows. Without ongoing investment, this will place increasing pressure on flood banks and river channels and may reduce the level of service they provide over time.
Work underway at Dipton West
Work at Dipton West began during the 2025/26 construction season. It was identified as a priority area for maintenance and repair, with enough planning completed for work to begin. It includes restoring sections of flood bank to their design standard, addressing deferred maintenance, removing invasive willows and other vegetation, improving channel performance and reinstating access tracks and ramps.
Flood bank construction and earthworks stopped in May 2026 because the ground had become too wet. Construction is planned to restart in late September 2026 and is expected to be completed in March or April 2027, weather permitting.
Maintaining this section of flood bank is important for the Dipton West community, surrounding productive land and key transport connections. Disruption to these connections during high river flows can affect residents, farm operations and emergency services and lead to reactive and often costly repairs.
Recently completed flood bank works near Dipton. Vegetation has been cleared from the flood bank, fencing has been relocated to improve grazing management, and the bank has been mown to promote healthy grass cover and support ongoing maintenance.
Further work planned for 2026/27
The 2026/27 work programme includes continuing at Dipton West and beginning further maintenance, repair and improvements across priority parts of the lower Ōreti flood infrastructure network.
Timing will differ between locations. Some packages can be progressed relatively quickly, while others require further investigation, engagement with affected landowners, design and consenting.
Environment Southland is meeting directly with affected landowners before publishing more detailed information about the locations and proposed work. This page will be updated once those discussions have been completed.
What people may notice
The work planned for 2026/27 will include further tree and vegetation removal. People may also notice more trucks, machinery and contractor vehicles using local roads and access routes.
No road closures are currently expected. Temporary traffic management and signage may be used where needed, and drivers should take care around work vehicles.
David Milligan Park remains closed
Public access to David Milligan Park remains closed while earthworks continue on the Ōreti flood bank beside the park and grass cover becomes established. The park is expected to reopen around Christmas 2026, weather permitting.
What does ‘agreed level of service’ mean?
‘Level of service’ refers to the performance standard a flood bank is designed to meet, including its height, stability and ability to safely convey floodwaters, rather than preventing flooding entirely.
Even when flood banks are restored to their agreed level of service, residual flood risk remains. Ongoing maintenance, monitoring and preparedness are essential parts of managing flood risk over time.
How has further work been prioritised?
The work at Dipton West was identified as the most urgent and began during the 2025/26 construction season.
Environment Southland has since completed a technical review to determine where further work in the Ōreti catchment should be focused during 2026/27. This review considered the condition and performance of existing flood banks, opportunities to reduce flood risk or improve how water moves through the river system, value for money and practical matters such as design, consenting and landowner requirements.
The review drew on site inspections, existing engineering assessments, information about Environment Southland’s assets and the local knowledge of its operational team.
Flood modelling of the Ōreti catchment is not yet complete. The focus for 2026/27 is therefore on further work that current evidence shows is needed and that can proceed without limiting future decisions about the wider network.
Will this work stop flooding?
The work will help restore agreed levels of service and improve the performance of priority parts of the Ōreti flood infrastructure network. It will help reduce the effects of flooding, but cannot remove all flood risk, particularly during larger events that exceed the network’s capacity.
Read more about flood risk in Winton and the level of service provided by the flood infrastructure network.
Why are the trees being removed?
Trees growing into the flood bank can weaken its structure. Roots can create pathways for water, and if a tree falls it can pull out a large root ball, leaving a weak point in the bank.
Trees in the floodway can also affect how water moves during floods. Broken trees and branches can travel downstream and become trapped against bridges, culverts or other structures, restricting flows or causing damage.
Where trees have grown into the flood bank, the stumps and roots are removed so the bank can be properly rebuilt and grass cover re-established to help protect it from erosion.
What is happening with the wood from the trees?
The wood has been removed from the site. Trucks bringing in new topsoil to reinstate the flood bank backloaded the felled timber so material could be removed efficiently.
For the wider project, a waste-minimisation approach is being used:
- usable logs and timber will be retained for landowner use where practicable
- smaller material will be chipped and removed from the site
- only residual, non-reusable material will be disposed of through controlled burning.
Controlled burning is a permitted activity under the Southland Regional Air Plan. Burns will take place in designated gravel pits under suitable weather conditions, with active supervision and on-site fire suppression. Work will stop if smoke or nuisance effects extend beyond the site. Neighbouring landowners and emergency services will be notified in advance.
Local involvement
Environment Southland provides regular updates about the Ōreti work directly to affected landowners and through the Ōreti Catchment Liaison Committee.
Even where progress is limited between construction seasons, the project remains a standing committee agenda item so landowners, councillors and river users can receive updates and provide feedback.
Local knowledge and feedback help inform delivery and future work.
See how local contractors contribute to flood infrastructure work across Murihiku Southland in the Envirosouth feature Holding the Line.
Local delivery: Stirling Contracting — Shane Dickson (centre) with Raymond Stirling (right) and Nathan Clarke (left) — delivering targeted upgrades on the Aparima and Ōreti flood banks.
What the funding supports
Government co-funding confirmed in October 2025 supports two connected types of work in the Ōreti catchment.
Some of the funding is being used to address deferred maintenance and repair existing flood banks so they can provide their agreed level of service. Other funding supports improvements to strengthen priority parts of the network. These improvements may include flood bank realignments, channel work, tree and vegetation removal and better operational access.
Together, this allows Environment Southland to address urgent maintenance needs while developing longer-term improvements to the network.
The work is co-funded with central government through Kānoa under the Resilient River Communities initiative and supported by the Regional Infrastructure Fund.
Flood modelling in the Ōreti catchment
Environment Southland is progressing flood modelling across the region, including the upper Ōreti catchment. The modelling will help us assess current levels of service, understand where flood banks may be vulnerable to breaching, and test options for reducing flood risk, including infrastructure improvements, nature-based approaches and changes in land use.
