Kaituna River Re-diversion Opening Celebrated
Tangata whenua, Maketū schoolchildren, and other locals gathered together today with contracting staff, Bay of Plenty Regional Council and Western Bay of Plenty District Council representatives, to celebrate the return of freshwater flows from the Kaituna River into Te Awa o Ngātoroirangi/Maketu Estuary.
Bay of Plenty Regional Council Deputy Chair Jane Nees acknowledged the efforts of tangata whenua, Regional Council staff, J Swap Contractors Ltd, Western Bay of Plenty District Council, and the many passionate locals that have been involved in the project since Regional Council first began exploring design options in 2013.
“Healthy waterways and environments are the foundation of a thriving community. This project has taken hard work, investment and collaboration from many local people and landowners over many years. It’s a great example of what can be achieved when everyone works together,” said Councillors Nees.
“Today marks a turning point for estuary health but it doesn’t stop here. We’ve got more work to do, and many other projects already underway, to keep improving water quality and wildlife habitat throughout the Kaituna catchment,” she said.
Bay of Plenty Regional Council Kaituna Catchments Manager Pim De Monchy said that the local community has been calling for freshwater flows to be restored to the estuary since the 1970s.
“There had been a noticeable decline in estuary health since the Kaituna River was diverted out to sea at Te Tumu Cut in 1956 by the Crown and Regional River Board for land drainage purposes. The estuary had silted up, become choked with algae, and birds and fish had lost their breeding and feeding grounds.
“Through this project, up to 20 percent (600,000m3) of the Kaituna River’s flows will now be returned to the estuary on every tidal cycle, while maintaining existing levels of flood protection and boat access through the Te Tumu Cut,” Mr De Monchy said.
Bay of Plenty Regional Council has invested $16.6m (including design, consultation, consenting and land acquisition costs) to complete the project.
J Swap Contractors Limited began construction work in June 2018 and have now completed it, on budget and five months ahead of schedule. They have widened the Ford’s Cut Channel, moved and upgraded stop banks, and installed a new 60 metre wide channel (one kilometre long) to carry freshwater from the Kaituna River into the Maketu Estuary via 12 large culverts, fitted with automatic gates, under the Ford Road bridge.
The contractors installed a new salinity block downstream of the new channel, to reduce saltwater intrusion into the upper estuary, and upgraded the Ford Road boat ramp facilities. They also re-contoured low-lying paddocks beside the upper estuary, to create 20 hectares of estuarine wetland. Volunteers have helped to plant the new wetland called Te Pā Ika with 65,000 native plants.
Mr De Monchy said that since 1956 it has taken 15 tidal cycles to flush the estuary with river water, but it will now take only two and a half tidal cycles when all twelve of the new culverts are open.
“For the first year of operation we’ll be allowing the estuary to adapt gradually by opening just nine culverts on each incoming tide, and monitoring that closely before we open all twelve.
“The increased flushing and improved salinity balance that the restored river flow will bring, along with the 20 hectares of wetland we’ve re-created, will help the estuary to recover and become healthier for fish and wildlife to live in, and people to enjoy,” he said.
See further project details and background information at www.boprc.govt.nz/kaitunarediversion
See below to access images. For further media information please contact Katrina Knill, Communications Partner on 0800 884 880 or 021 989 666.
In 1956 almost all of the Kaituna River’s flow was diverted away from Maketu Estuary and out to sea via Te Tumu Cut, to support drainage of the low-lying farmland in the area and protect it from flooding.
In 2013, in response to community concerns about the declining estuary health caused by the diversion, Bay of Plenty Regional Council began feasibility studies and consultation on more than 18 different river re-diversion options. Councillors approved funding for a preferred option in 2015, and staff have since worked together with local landowners, tangata whenua representatives, and J Swap Contractors Ltd to complete the Kaituna River re-diversion and Te Awa o Ngātoroirangi/Maketu Estuary enhancement project.
The goal of the $16.6m project has been to significantly increase the volume of water (particularly fresh water) flowing from the Kaituna River into Te Awa o Ngātoroirangi / Maketu Estuary, in a way that maximises the ecological and cultural benefits (particularly wetlands and kaimoana) while limiting the economic cost and adverse environmental effects to acceptable levels.
Construction facts and figures:
Construction work on the Kaituna River re-diversion and Te Awa o Ngātoroirangi/Maketu Estuary enhancement project has involved:
- c.50,000 person hours by J Swap Limited staff and contractors.
- The use of 25 different excavators, trucks and other heavy machines.
- Planting of 65,000 wetland plants with help from community volunteers.
- Laying of 800m of new electrical cable and 404.1m3 of concrete.
- 110,000 tonnes of gravel, sand, rocks and clay brought to site through 2704 truck movements.
- 152,660m3 of earth dug out to create new river channel.
- Installation of 12 new 2.5m x 2.5m concrete culverts and automatic flow control gates.