Residents decry lake decline
A Golden Bay lake has become an unswimmable, contaminated mess and residents say stormwater from a nearby dairy farm and housing is to blame.
For the past two summers significant algal bloom, or cyanobacteria, has been increasing in Lake Killarney, nestled in a reserve behind Commercial St near the town’s centre.
Since 2004 stormwater from neighbouring farmland and residential properties has been diverted into the lake.
Resident Dave Kennedy said the lake was ‘‘clear blue’’ when he shifted there 30 years ago, but these days it was often a ‘‘murky brown’’.
‘‘I think it’s only since they directed the stormwater into the lake that it’s started causing the harm,’’ he said. ‘‘Our kids used to swim in it, but you wouldn’t like to now.’’
While sediment analysis is due next month, Tasman District Council (TDC) results to date reveal a ‘‘significant’’ nutrient and organic contamination.
Takaka residents bordering the reserve are increasingly concerned about the discolouration and potential effects of the algal bloom on adjoining properties.
John Lewis said the lake was still very blue when he moved there five years ago, but in the past few years he had noticed the discolouration increase during the summer months and after rain.
‘‘You wouldn’t like to stick your toes in there now,’’ he said.
Lewis is taking regular water samples and photographs for the council, whose engineers are trying to solve the problem.
He said the contamination was coming from the council-owned pipe, which was draining from a sump on the adjacent dairy farm previously owned by Fonterra, and into the lake.
Algal blooms are typically the result of a build-up of nutrients and need warmth to grow. Another potential source was from the leaves of deciduous trees, he said.
During heavy rain several weeks back, his wife Anne Lewis said she noticed water coming out of the drain was ‘‘the colour of mud’’.
TDC spokesman Chris Choat said it had applied for Envirolink funding to get advice on developing a more comprehensive plan ‘‘to inform us’’ and for remedial options. ‘‘It’s not toxic at this stage, but we would advise people to avoid contact with the water.’’
Stormwater and runoff from a neighbouring farm and residential area have turned Takaka’s Lake Killarney into a discoloured mess.