The Otago Regional Council is seeking answers to the
declining water quality of the Tokomairiro River near Milton.
The move follows the release of the Otago Regional Council's
(ORC) State of the Environment study of water quality and
ecosystem health in the Tokomairiro catchment.
The Tokomairiro River runs alongside Milton in South Otago
and ORC director of environmental information and science,
John Threlfall, said the water quality of the Tokomairiro
catchment was steadily declining.
A seven-month study, which began in August last year,
revealed that water quality has deteriorated significantly in
recent years, with the entire catchment exceeding guidelines
for bacteria, sediments, and nutrients.
The Moneymore drains were the most polluted sites in the
catchment and contributed to increases in pollution
downstream of their confluence with the west branch of the
Tokomairiro River, Dr Threlfall said.
In the east branch, most of the water quality degradation
came from the Gorge Creek and Salmonds Creek catchments.
Intensive farming and poor land use practices were the main
causes of the degraded water quality and poor ecological
health, Dr Threlfall said.
Run-off from State Highway 1 after heavy rain was also a
contributing factor, although not to the same level, he said.
The report on the Tokomairiro area, which had a long history
of agricultural use, said the climate and soil type meant
that farming in the catchment relied on artificial drainage,
specifically open and tile drains.
However, the regional council says changes in land use -
especially in the lower catchment where dairy farm
conversions are common - combined with inappropriate land
management, are putting pressure on the water quality. This
is also threatening the river's natural values, including
native fish, five of which are considered to be endangered,
and a trout fishery.
The monitoring carried out by the council between 2001 and
2006 led to the Tokomairiro River at the west branch bridge
being classified as having good water quality. However, water
quality declined sharply between 2006 and 2011, reducing its
classification from good to fair, and making it one of the
most polluted rivers in Otago.
The ORC has organised a public forum in Milton on Thursday to
help farmers in the Tokomairiro address and resolve the water
ORC chairman Stephen Woodhead said the forum was a chance for
locals to hear about the water quality results and discuss
solutions, as well as a chance for farmers to learn what they
need to do to be compliant with the Otago Water Plan.
''Most locals understand that this sort of degradation of the
waterways cannot continue. Unfortunately, it is a reality
that some of the local farm management practices are
contributing to the problem,'' Mr Woodhead said.
The council was keen to work with the local farming community
to identify solutions to those problems, he said.
Tile-mole and surface drains are extensively used to enable
farming on the catchment's heavy clay soils, and it was these
drains which were often the conduit for most of the
contaminants being discharged into the waterways.
The ORC accepted that these were not easy issues to solve but
a start had to be made, and it was crucial that people got on
board with improving water quality in the area, Mr Woodhead
''Changing some of the practices which have caused the water
pollution doesn't require rocket science. With commitment
from local landowners, this catchment can be rehabilitated.''
ORC would prefer not to go down an enforcement path, and
hoped the Tokomairiro community would work with the council
to identify practices which would ensure farm activities
complied with ORC rules.
• Tokomairiro water quality forum,
White Horse Inn, Milton, Thursday, December 13, 7pm to 9pm.