Located just north of the Waitaki River, the Waikakahi became the poster stream for the dirty dairying campaign in the late 1990s.
Stock grazed along its banks and at times right into the stream, leaving a muddy, barren landscape in winter.
But now it could be the poster stream for what can be achieved when a community comes together, where there’s good monitoring and science, and where simple but effective good management practice comes into play.
The before and after photographs paint a stunning picture of what’s been achieved with almost all the stream’s 16km length fenced off from stock.
Both community and farmer-driven riparian plantings have created effective filtering zones for nutrient run-off and provided shade to enhance the in-stream environment.
Where there was once a silt-choked, often discoloured waterway a shingle bottom has returned in many places and the water runs clear – clear enough to spot good-sized trout cruising in numerous pools along its length.
Chris Paul and David Crooks recall the early community meetings, many of them with a fair bit of heated debate and finger-pointing to start with.
Paul says dairy farm numbers were on the rise in the area and farms were irrigated almost exclusively by borderdyke irrigation.
In some cases the water flowed off the ends of the borders and sooner rather than later ended up in the stream or its tributaries.
It was common practice to graze right into streams and creeks to keep the grass down and in some cases farmers used waterways as stock water.
“I think there was a mixture of knowing we had to do something to improve the stream’s health but a bit of defensiveness too because we didn’t know what the fixes were going to be when we went along to those first meetings,” Paul says.
The key to getting action was everyone did get around the table and talk, and water quality data was collected so the discussion could be based on facts.
Former Waitaki Zone committee chairman and local dairy farmer Robin Murphy agrees both factors were vital not just in getting initial action but also in keeping farmers and the community engaged.
It’s not a quick-fix problem and Murphy says there’s no silver bullet either.
“Even though we started fencing and planting and farmers were taking action on their farms the quality of the water still kept declining early on,” he remembers.
Then the decline halted and from there a lot of the water quality parameters, tested and monitored on a regular basis, began to improve.
The Waikakahi catchment is part of the best-practice dairy catchments study, which began in 2001 and also includes the Bog Burn in Southland, Toenepi in Waikato, Waiokura in Taranaki and Inchbonnie on the West Coast.
‘The Waikakahi really is a prime example of the community working collaboratively together to achieve good outcomes.’
Extensive water quality data has been collected regularly in each catchment to monitor the effects of introducing a range of best management practices.
In the early years nutrient budgets, fencing of streams and managing grazing to prevent pugging were considered best practice.
Now nutrient budgeting is a mandatory condition of milk supply for most dairy processors and several of the “best management” practices are considered
simply as good management or even everyday management.
Niwa principal technician for freshwater ecology Aslan Wright-Stow says data collected over the 10 years of the best-practice dairy catchments study showed a four-fold decrease in sediment loading in the Waikakahi Stream.
Levels of E. coli bacteria dropped and water clarity also improved.
But not all water quality indices improved. Nitrogen levels increased over the period and concentrations continue to sit among the top quartile compared with other waterways.
But Wright-Stow points out the results should also be taken in context of a rapid increase in cow numbers in the catchment over the period.
For instance the New Zealand dairy statistics show over the study period from 2001 to 2011 cow numbers in the Waimate district, which includes the Waikakahi, almost trebled.
Niwa’s also been following the population levels of invertebrates in the stream and hasn’t yet seen the increases that might be expected.
Cawthron Institute freshwater ecologist Robin Holmes has carried out further monitoring on stream health more recently and says despite the invertebrate levels not increasing as expected fish and eel life has returned.
That raises questions over how stream health is measured and what metrics the community looks to when it’s setting targets for water quality.
In the case of the Waikakahi invertebrate numbers alone would suggest little improvement but if the community’s values are based around water clarity and fish life then it’s getting the stream to where they want it.
Holmes says some of the best stream areas in terms of the in-stream environment are notably adjacent to and below sections of the stream with wider fenced-off riparian zones, Holmes says.
Three to five-metre riparian zones are proving to give the best results.
While planting will enhance that further the biggest, fastest gains come simply from fencing the riparian zone off and allowing rank grass to grow.
Holmes hopes to secure funding to continue monitoring stream health indices so more is understood about in-stream responses to what’s happening onfarm and in the catchment, so farmers and the community can have sound facts on which to base their activities and plans.
Both Holmes and Wright-Stow say what’s been achieved since the early 2000s is significant given the very long time-frames typically associated with ecological recovery.
What makes it even more significant is the dairy industry in the area has continued to grow.
Murphy agrees continued monitoring is essential so the community, including farmers, can see their efforts are keeping stream health heading in the right direction.
When the best-practice dairy catchments study came to an end about four years ago and final results were presented to the community, Murphy says people wanted to know what they had to do next to bring about further improvements.
In a sense the changes farmers made were the low-hanging fruit. Fencing off streams, doing nutrient budgets, and maintaining soil phosphorus levels within the optimum zone for pasture production rather than letting them get too high all had a relatively fast and big impact on stream health.
So too did the widespread shift from borderdyke to spray irrigation.
While there are probably still gains to be made by ensuring good management practices are used as a matter of course, the next step up in stream health is likely to need new developments.
Murphy says new silt trap designs developed in another catchment in the area were an example.
He farms in the lower reaches of the Waikakahi and while his onfarm investment has included putting in a bridge, he says on the whole farmers haven’t had to spend “mega-dollars” to get the stream to where it is.
Lower Waitaki South Coastal Canterbury zone committee chairwoman Kate White says the committee is continuing to support work Holmes is doing in the stream catchment.
“The Waikakahi really is a prime example of the community working collaboratively together to achieve good outcomes,” she says.
Having good science that’s then used to develop and back-up practical solutions has been a significant part of the success in the catchment, she says.
Once farmers understand the problem they just want to know what has to be done to fix it, she says.
The dairy industry had been particularly pro-active and willing to work with the scientists and wider community.
The catchment is an example to others in the region and White says the zone committee hopes to be able to extend the work Holmes has been doing into other areas.
