Canterbury’s Otukaikino River took out the Supreme Award for Most Improved River at the New Zealand River Awards 2018 in
Dr Morgan Williams, Chair of Cawthron Foundation and NZ Rivers Trust, says that this year phosphorus was the indicator
used to determine the most improved river, with trends in other key indicators also being examined. Otukaikino River,
located on the outskirts of Christchurch, has very good water quality with its phosphorus levels decreasing by 17.5
percent per annum over the past ten years. Levels of ammoniacal nitrogen, total nitrogen and total oxidised nitrogen,
have also decreased.
Biological and chemical indicators are used to provide information about a river’s overall health, its ability to
provide a habitat for many species of plants and animals and a recreational place for communities. Ideally, these
indicators will give an early warning of changes that are affecting a river, enabling them to be addressed.
“The challenge is to effectively combine the health implication of a number of indicators with varying degrees of
interaction and ultimate impact,” says Dr Williams. “Science, goodwill, and hard work can help restore river health. I
am encouraged as councils, communities and individuals recognise that the cumulative impact of many actions can help
river health. However, for collective effort to be even more effective, we require a step change, not only in terms of
what we are measuring, but how we are measuring it. There is urgent need for indicator measurement in real time, as
current occasional sampling misses many events, such as silting or low oxygen levels, that have big impacts on river
The deep spring-fed Otukaikino’s catchment has received long-term attention from two Councils, local businesses,
Community Service workers, landowners and community and industry groups. These efforts have resulted in an environment
that is now a popular recreation spot.
Sixteen years ago, a planting and fencing programme commenced after a Christchurch City Council (CCC) ranger had
conversations with landowners about water quality. These conversations led to farmers fencing off land to prevent stock
entering the waterway and within a few years there was a buffer zone of between 20-100 metres. This made way for an
extensive planting programme, which has been a key factor in reducing phosphorus.
For much of this time, the regional council – ECAN – has also been actively involved. However, it is the wider community
that have been the real champions. The following agencies have provided plants, funding, or participated in planting and
weeding days: ECAN, Christchurch City Council, Christchurch West Melton Zone Committee, DOC, QEII Trust, Trees for
Canterbury, Z Energy (Aviation), local schools, scout groups, Fish & Game and private landowners like Isaac Conservation Trust and Clearwater.
Weeding and maintenance is also important. Department of Corrections Community Service workers have cleared willow,
blackberry, gorse and broom, then planted and mulched banks. Their efforts have been augmented by local scout and school
groups, plus an annual Trees for Canterbury Planting day.
Today, nearly the entire length of Otukaikino River is fenced – estimated to be around 10km – meaning stock can’t access
the water. It is estimated that 195,000 native, locally-sourced plants have been put into the ground.
The river shows positive water quality trends for dissolved phosphorus over the past ten years. In addition, total
oxidised nitrogen, total nitrogen, and ammoniacal nitrogen show an improvement.
A consistent champion of the Otukaikino is CCC Park Ranger, Arthur Adcock.
Arthur says addressing water quality is a priority, and improvement to date can be put down to a team effort. In
particular, he wants to acknowledge the support from community service supervisors and landowners.