Lake bloom fix could cost $100m
A brass-coloured lake in North Waikato may need a $100 million solution, according to one Waikato Regional Council ecologist.
Lake Waikare, the largest lake in the Waikato, has been different shades of pink and copper for four months because of algal bloom, and council ecologist Bruno David says there's no simple answer.
''This will require an industrial engineer-type solution on a scale that's never been undertaken before in New Zealand,'' David said.
''This is the sort of thing where it's going to cost maybe $100m - if you were to undertake dredging to make the lake deeper.''
David said the lake was a vital part of the area's ecosystem.
Farmers depended on it for irrigation and it serves as part of council's Flood Protection Plan for the Waikato, used as a catchment to drain the Waikato River during peaks.
''They have targeted rates with farmers to maintain the [flood protection] scheme, but there's no money to do anything on top of that.''
Long-time Ohinewai farmer Malcolm Lumsden said a rates hike that high would kill his business - a 425 hectare dairy farm.
''We can't afford that. But that's just a silly comment, that's off-the-shelf stuff, I couldn't use kind words to describe how I feel about that at the moment.
''I know we're already paying in excess of $5000 a year in rates.''
Lumsden agreed a solution must be found to the murky problem.
''Without Waikare, the flood protection scheme wouldn't work - there's 37,000ha of land it protects.''
Lumsden recently retired from the Lower Waikato Liaison Advisory Committee for Waikato Regional Council and said the formula for improvement would not be easy.
''Over the years we have set up endless committees to look at what we can do to improve the quality of the lake and there's no easy solution.''
''It's a terrible shame it's got to this. We have had two very hot summers and with the very low levels, I guess it heated the water.''
He said Waikare was an ash pit, left over from Taupo eruptions, and geothermal vents were active along its eastern foreshore.
''There have been changes on the farm here with material coming out of old bores and it's killed the grass. There's no explanation for that.''
David said Waikato University and the National Institute of Water and Atmospheric Research (Niwa) had been working on identifying the algae