Steady progress helps reduce Kaipara’s erosion risk

Progress is being made but plenty of work remains in the longstanding battle to minimise erosion on Kaipara hill country and reduce sedimentation of the sensitive Kaipara Harbour and waterways.

The Northland Regional Council (NRC) has just completed the second year of the four-year Kaipara Hill Country Erosion Project (KHCEP). Targets have been exceeded so far with 54 farm plans produced for farms with a high risk of erosion, covering nearly 16,000 hectares within the Kaipara catchment. In addition, 48ha of pastoral land with high erosion risk has been retired from grazing through recommendations made during the farm plan process.

The milestones have been achieved with funding from the Ministry for Primary Industries' (MPI) Hill Country Erosion Fund, established for regional projects that help hill country farmers treat erosion-prone land and implement sustainable management practices. The NRC received a $666,000 share of the fund in 2015.

"These are encouraging results that are a credit to our land management advisors and the landowners they are working with," the council's chairman Bill Shepherd says. "It's very much a hands-on effort for our advisors who are working direct with Kaipara farmers on their soil conservation initiatives."

"I think this shows what can be done when people work together with a common goal. We've made a start on reducing Kaipara's erosion, though it will be some time before we see significant results in terms of reduced sedimentation in the harbour. This is a long-term project to right a long-term problem."

Research throughout New Zealand has found poplar trees are the most efficient and economic tool for reducing soil erosion in hill country and the supply and delivery of 3840 poplar poles to 39 Kaipara landowners is nearing completion.

The KHCEP contributed $20,000 towards the poplar poles, which are delivered to landowners at no cost. Landowners contribute the same amount in-kind, mainly in time required to plant the poles.

Each landowner works closely with a council land management advisor who provides them with a detailed planting plan outlining where the poplars should be planted and information about how to handle, plant and maintain them for best results.

A further 138ha of high erosion risk land in the Kaipara catchment have Afforestation Grant Scheme (AGS) applications pending with MPI. These grants are for new forests as part of an MPI programme to reduce soil erosion, improve land-use productivity, store carbon and improve water quality.

The MPI funding has also allowed the council to undertake research with the aim of producing guidance on the options for landowners in the management of mature poplars and willow trees, and the development of an online cost/benefit calculator for alternative land uses on highly erodible land.

The MPI funded initiatives are part of a larger effort to control erosion and sedimentation in the Kaipara catchment where 23 percent of the 474,000ha catchment is identified as hill country with high erosion risk.

In the last year, 85 Kaipara properties have received funding of $361,490 from the council's Environment Fund (EFund) for projects involving fencing of waterways, retiring steep and unproductive land, and planting riparian margins and erosion prone land. Farmers have matched the council's 50% contribution to the real cost of the projects, contributing the same amount, or often more, in-kind.

Community groups within the catchment are actively involved and include Waiora Northland Water catchment working groups (Pouto and Mangere catchments) and the Integrated Kaipara Harbour Management Group (IKHMG), which brings together hapu, councils (including Auckland Council), research agencies, industry, farmers, fishermen and other stakeholders to create a healthy and productive Kaipara Harbour.

In addition, the council is leading a Kaipara Harbour sediment mitigation study funded by the Ministry for the Environment and involving NIWA, Landcare Research, Streamline Environmental and Auckland Council. This two-year project is improving understanding of the sources and ecological influences of sediment on freshwater and harbour systems.