July’s featured river is the Mangere River in Northland, one of the priority rivers being addressed through Northland Regional Council’s Waiora Northland Water programme.
The Mangere Catchment lies approximately 12 kilometres west of Whangarei. Slow-flowing through an area of intensive agriculture, the Mangere River begins at the Mangere Stream, flowing out of the Pukenui forest near Whangarei, and becomes a river on the flats before joining the Wairoa River near Kokopu.
The catchment has been monitored by the Northland Regional Council since 1996, and is rated in the bottom 5% of Northland's monitored rivers and among the poorest 25% of New Zealand’s lowland rural sites for five of the nine parameters displayed on LAWA.
Intensive agriculture is a key contributor to the levels of bacteria and nutrients in the river. Although there is a thin forested strip along much of its length, with totara trees providing good shade, stock grazing has reduced the understory vegetation which helps filter run-off from the land. In places, stock also have direct access to the river, resulting in unstable banks and increased sediment in the river. Consequently, the quality of the stream is compromised.
However, there are positive signs the Mangere River’s water quality is improving, with significant reductions in nutrient levels achieved over the past nine years through the efforts of the local community.
Community comes together
In 2012, Northland Regional Council launched Waiora Northland Water, a programme for improving the quality and management of Northland’s lakes, rivers, aquifers and wetlands. It brings together a number of the council’s water management responsibilities.
At the heart of Waiora Northland Water are catchment groups, with members representing the interests in each catchment: iwi and hapu, farmers, industry (such as energy or quarrying), residents, environmental groups, recreational interests and local authorities.
The Mangere catchment group is one of five formed throughout Northland. It has 16 members, including four iwi representatives, four farmers, three local residents, a representative of an environmental group and four district or regional councillors (including Northland Regional Council chairman and longtime dairy farmer Bill Shepherd).
The group’s membership is reflected in its appointment of co-chairs to achieve balance in its leadership: iwi representative Tania Pene and dairy farmer Royce Kokich. An early activity for the group was a guided stream health investigation field trip, starting at a small tributary high up in the catchment and finishing downstream of the Mangere Falls. The objective of this field trip was to ensure group members began with consistent information about in-stream values. They worked side-by-side to measure water quality, temperature and clarity, check fish traps and sample macroinvertebrates.
Co-chair Royce Kokich said that encouraging farmers to participate was easy as they share the goal for the improving the river.
“Dairy NZ was very supportive and brought the farming community together but most farmers were keen to be involved as they want a healthy and productive environment as much as anyone,” explained Mr Kokich.
The Mangere River drains a large number of dairy farms which are continuing to upgrade their effluent disposal systems. All but two of the 22 dairy farms in the catchment now use systems that apply effluent to land unless conditions are exceptionally wet. The benefits of these upgrades are evident in the indicators for ecosystem health and recreation, which are all either stable or improving. In some cases, positive changes have been very large, for instance, there’s been a 32% reduction in ammonia at the Mangere River at the Knights Bridge monitoring site since 2007.
As well as upgrading systems, farmers have been fencing off waterways and, in some cases, undertaking riparian planting.
"Riparian planting and additional fencing is something for us to work on,” Mr Kokich acknowledged.
“We’re just starting out so our initial focus has been on making the changes that result in the biggest difference.”
Mr Kokich has begun doing some riparian planting and has also fenced off some particularly wet areas on his farm that aren’t so productive but act as a good filter of sediments and nutrients. He’s hoping that improvements in the catchment’s water quality will see the return of kokopu, a native fish he remembers inhabited the area’s waterways in his childhood.
The responsibility hasn’t solely rested with farmers, community groups and iwi have been undertaking pest control and riparian planting in the wider catchment, all of which contributes to an improved environment.
Looking forward
Despite the efforts to date, the group recognise that the catchment’s water quality is still impacted and ongoing land management changes are required.
Within the group, like any community, there are different values and expectations for the river.
Mr Kokich said the next steps were to agree on the values they want upheld. He acknowledged that there might be some differences among the group that would need to be worked through but he’s glad it hasn’t been holding them back from making a difference.
“We still need to discuss what our values for the river are but that hasn’t got in the way of us getting stuck in and making changes on farm and around the river that are going to lead to the improvements we all want to see.”
Northland Regional Council chair Bill Shepherd said that working with water bodies like Mangere is one of the regional council’s top priorities.
“Through Waiora Northland Water we are protecting our most pristine and precious waterbodies, looking at catchments with the poorest water quality, and working on the areas where there’s the best opportunity to make a real difference,” said Mr Shepherd.
“Although the programme is still in its infancy, hands-on involvement and collaboration at local community level is key to securing the future health of catchments such as Mangere.”
Northland Regional Council has established an Environment Fund which it hopes communities like Mangere can benefit from. In recent years, the fund’s main focus has been on supporting projects that will help to improve water quality in rivers, lakes, wetlands and coastal environments. Eligible projects have included stream, lake and wetland fencing; wetland and lake restoration projects; soil conservation projects such as planting of poplars and willows and fencing of erosion-prone land; and riparian planting.
Looking for more information?
You can read more about the Mangere Catchment and the community group’s efforts at the following links:
For further information on Waiora Northland Water, visit www.nrc.govt.nz/waiora
For further information on the Mangere catchment, visit http://www.nrc.govt.nz/Resource-Library-Summary/Catchment-groups/Mangere/
For more information on the Northland Regional Council Environment Fund, visit
www.nrc.govt.nz/environmentfund