Horowhenua (Waiopehu) Water Quality Interventions

On this page:

 

• Community meetings
• Current state of the Horowhenua (Waiopehu) FMU
• What we're doing to help
• Horowhenua constructed wetland complex conceptual design
• Environmental data
• Reports and related documents

Community meetings

Community meetings were held in November 2022 to discuss the conceptual designs for the constructed wetland complex near Lake Horowhenua. 

The first round of submissions has been received, if you would still like to provide feedback email horowhenua.wetlandcomplex@horizons.govt.nz or calling us on freephone 0508 800 800. 
 
The presentations and minutes from these meetings are also available below.

What we're doing to help

The current interventions work around Lake Horowhenua was boosted by the Mahi mō te Taiao – Jobs for Nature Horowhenua (Waiopehu) Freshwater Management Unit Water Quality Interventions project (2021-2024). This support comes from Central Government funding and is complemented by Horizons Regional Council (a total of $12.5 million; $11.2 million from Central Government and $1.3 million from Horizons).
 
One of the key objectives for this project is the construction of a wetland complex in the Arawhata sub-catchment of Lake Horowhenua. The project also aims to further characterise the surface and groundwater of the FMU to improve understanding of the flow paths to Lake Horowhenua, connections between catchments within in the FMU and the state of the Ōhau and Waikawa estuaries.
 
Another objective of the project has seen a Governance Group established which includes Horizons Regional Council, Horowhenua District Council, Muaūpoko Tribal Authority, Te Rūnanga o Raukawa, Lake Horowhenua Trust, and Ministry for the Environment representation.
 
The wetland complex will be constructed to improve the mauri and water quality of Lake Horowhenua with Te Mana o te Wai at the forefront of the project. It will also consider economic, social and recreational opportunities in future development. Horizons has purchased a 142ha dairy farm in the Arawhata for this purpose.
 
A Wetland Design Group and a Mātauranga Rōpu (Kāhui Ārahi) have been established to develop the wetland design and a Community Stakeholder Group has also been formed with input from this group to be considered in the process.
 
This work leads on from the Lake Horowhenua Accord established in 2013, where five parties representing Muaūpoko owners, community interests and statutory bodies agreed to work together to provide leadership and halt degradation of Lake Horowhenua and Hōkio Stream. Past and ongoing initiatives, and funding, include investments in sediment traps, lake weed harvesting (see the video below), fish passage around the Lake Horowhenua weir, riparian fencing and planting, working with horticultural growers in the Horowhenua District to maximise nutrient use and reduce leaching to waterways, and developing sediment and erosion control plans for horticultural growers.

Horowhenua constructed wetland complex conceptual design

The initial conceptual design for the Horowhenua constructed wetland complex has been completed and the project team is now seeking community feedback.

The initial wetland complex construction will help to reduce the concentrations of nitrogen, sediment and phosphorus within the water and therefore the amount of contaminants that enter Lake Horowhenua from the Arawhata catchment. This combined with the other interventions both within the catchment and the lake itself will improve the water quality within Lake Horowhenua.

The conceptual design includes a master plan for the constructed wetland complex which is then split into three phases.

The first phase aims to convert at least 15 hectares of farmland into a constructed wetland complex by December 2024.

As further funding becomes available the following two phases will be considered. These phases will extend the constructed wetland complex  

The constructed wetland complex will incorporate plants historically found in this area prior to its clearance, species such as Harakeke (flax), carex, and rushes.

Environmental data

Horizons measures a variety of water quality parameters across the FMU. This data is provided to the public via the Land, Air, Water Aotearoa (LAWA) website. Click on a link below to explore the data for that catchment.