Wednesday, February 21, 2024

Project helps farmers clean up blighted estuary

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Fifteen Bay of Plenty landowners supported to transition to lower-footprint systems along Waihī Estuary.
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A project to support 15 Bay of Plenty farmers to transition to lower-footprint systems has contributed to improved awareness of water quality in one of New Zealand’s most degraded estuaries. 

The two-and-a-half-year lighthouse project, completed in June, was part of the ongoing Wai Kōkopu community-led programme to improve the health of the heavily impacted little Waihī Estuary at Pukehina on the Bay of Plenty coast.

The project, funded by the Ministry for Primary Industries’ Jobs for Nature fund, used farm systems analysis, on-farm field days and expert advice to help the 15 farmers transition. This was  aided by the creation of a “pan sector digital farm plan”, which aimed to front-foot impending regulations and help farmers to be fit for the future. 

Alison Dewes, owner of Tipu Whenua, which provides farm system services for Wai Kōkopu, said the lighthouse project and drinking water monitoring have raised awareness of the scale of the challenge ahead.

“It aimed to assess how far farmers in the catchment could select management practices that reduced their impact on one of the worst five estuaries in New Zealand and what it would take to get it to a moderately healthy state,” Dewes said.  

“This work involved collaborating with over 60 different agencies and organisations, including all sectors of industry, health agencies, Crown Research Institutes, NGOs, iwi and hapū, foresters and restoration teams, while also watching closely what was emerging with regulatory changes.

“Contaminant load reductions included dropping the nitrogen (N) load by 70% and phosphorous (P) by 30 to 40% while also significantly reducing sediment and E coli – which is fairly consistently sitting at four to five times above safe levels.

“Overall, the scale of reductions of contaminants is significant in the estuary and receiving water bodies, and shallow aquifers are to return to a moderate state of health.

“Our team has also done a significant amount of drinking water testing for rural landowners, which links human health to environmental health. 

“It is not just the estuary that is enriched with nitrogen, but around 25% of the rural drinking water sources we have checked have indicated some contamination.”

The Waihī Estuary catchment features three rivers, which wind through steep-to-rolling hill country before flowing into the Little Waihī Estuary. The catchment has a variety of land uses, including dairy and support land, plus forestry, kiwifruit, avocados, sheep and beef and native forest.

Dewes said improvements to date include around 210ha of steep erosion-prone land being afforested in the mid to upper catchment, resulting in 10t less nitrogen and 1.6t less phosphorus getting into waterways – although there are more than 6000ha of steep erosion-prone land in the upper catchment that will ideally move into some sort of forest or native plantation over time.

Other big wins farmers are focused on include implementing best practice for effluent, more precise nitrogen and phosphorus use, diversifying plant species, enhancing soil health and becoming more familiar with the role of forestry or plantations on their land.

“In the lower catchment there are multiple challenges, with storm type rainfall events creating flooding and waterlogging, compelling us to seriously consider diversifying land uses or significantly improving mitigations, as climate changes. 

“This is not just a coastal Bay of Plenty problem, but a New Zealand-wide challenge. In most catchments, we need to slow the flow of water in the upper reaches, and enhance the flow paths in the lower areas.”

The start of the Pukehina canal collects in the lowest-lying 16ha of lower-catchment farmer Hamish Henderson’s grazing block, creating challenges with grazing management especially after the last very wet 18 months.

He said learning about the damage to groundwater from his farming activities has been an eye-opener.

“Wai Kōkopu has provided the information and incentives to take the need for change seriously.”

Two years ago, to help address the impact of land use on water quality, the Hendersons retired 2.5ha of boggy marginal land into a wetland with high ecological value. 

Farmer Paul Hickson said he has learnt much from the involvement with Wai Kōkopu as a lighthouse farm – although the Hickson family were already on a journey of diversification into horticulture, farm forestry and native plantations.

The Hicksons’ dairy unit has been reduced to 68ha effective, and the farm now has several hectares of native planting, plus riparian planting along streams and a significant wetland. 

“We are now gaining a better understanding of the various impacts of our activities such as nitrogen and phosphorus loads and losses to the environment,” he said. 

“We are continually trying to reduce our synthetic fertiliser inputs and move to lighter-footprint farming methods, in line with what we have learnt from our venture into organic kiwifruit development on the farm and our involvement with Wai Kōkopu, as a lighthouse farm.”

Dewes said it is important that farmers doing good work are rewarded and incentivised as part of the government’s Freshwater Farm Plan programme.

“Since February 2021, our catchment programme has worked with leading farmers to deliver 45 farm plans, helping farmers to lighten their footprint and prepare for change.

“The farm planning work done meets all the requirements for the Freshwater Farm Plan and more, in that it is agile, digital, has catchment context, and has time-bound actions, along with the farmers’ stories, that can be updated as work is completed.

“Over 40 pastoral farmers now know their GHG, N Loss, and P loss numbers – assisting them with change.

“By this spring, we anticipate we will have restoration of over 200ha of vulnerable land, from pasture into natives or exotic forest and 200,000-plus native trees planted.

“Twelve hundred water samples have been taken to understand trends in sites of concern and 60 rural drinking water samples on rural land tested, and owners alerted to issues.

“We have facilitated seminars on GHG, carbon farming, restoration, water monitoring, policy changes and working on what will make farms ‘fit for the future’. 

“A digital farm planning tool has also been developed. This covers all enterprises and offers a new way to capture great farming stories and plan for future compliance.”

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