A Waikato Wetland Showcase
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A Waikato Wetland Showcase

Gary Baldwin

Farmers around the country are under increasing pressure to improve the ways they deal with nutrient runoff from their properties.  In 2012 DairyNZ and Fonterra approached farmers in the Karapiro catchment, offering to help them document plans for nutrient reduction.  Dairy farmers Gray and Marilyn Baldwin had won the Ballance Supreme Environmental Award in 2009 for their efforts to protect the environment on their property and when they were approached, Gray suggested they go further and construct an experimental wetland.

Dr David Burger is the water quality scientist from DairyNZ leading the wetland project.  Wetlands are very good at filtering out sediment material and taking out waterborne nutrients, particularly nitrogen, through plant uptake or bacterial activity.  David says what isn’t well understood are contaminant removal rates under different environmental conditions and over differing time periods.

David took a proposal to the Waikato River Authority who backed it with substantial funding, along with NIWA, Hill Laboratories, Opus and the Waikato Regional Council.

The Baldwin Family Trust fenced off the wetland area and put it into a QEII Covenant.  Other sponsors contributed to excavations, plantings and instrumentation.  Construction began in autumn 2015 and community volunteer groups put in around 12,000 plants.

David Burger describes it as a series of rice paddies but on a much larger scale. The system is continuously monitored with automated flow recorders, and bottles (that can be triggered by cellphone or computer) collect a series of samples during high flow periods after rainfall.

Marilyn Baldwin is on the DairyNZ Environmental Leaders’ Forum and committed to helping farmers mitigate the impacts of farming operations.  She says, “We thought, let’s get a wetland in and be a learning tool to others.  It doesn’t need to be on such a grand scale but we all need to take action.  We want our children to be able to keep farming here so we need to be proactive in solving these problems.”

Gray Baldwin agrees cost is a major consideration.  “At present a lot of dairy farmers are hunkering down just to survive but they are still expected to comply with changing environmental rules and society’s expectations.  We have the land available for this project but not every farmer has natural wetlands or a spare sloping area where wetlands can be constructed.”  Gray adds, “For farmers looking at what we’re doing and saying, “Gee what’s that going to cost?” I think we’ll find there’s some very competitive ways of making it happen.”

“An alternative is to pour a lot of concrete and put the cows in a barn, collect the solid and liquid effluent in a tank and then apply it to the land when you can and store it when you can't.  That may be a more foolproof option but it may be a lot more expensive than constructing a wetland.  The debate will be around how cost-effective a wetland is in terms of removing nitrate versus building concrete pads and collecting effluent to apply during the dry months.  Hopefully the results from our project will give some insight into this.”

The Waikato Wetland Showcase story was first shown in episode 21 of Rural Delivery, first screened on Saturday 23 July 2016 and available to view on TVNZ on Demand.

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Rural Delivery: www.ruraldelivery.net.nz

TVNZ on Demand: www.tvnz.co.nz/ondemand

Do you have an experience in regenerating or constructing a wetland?  Can you share some advice for those wanting to begin?