By Hayley Gastmeier
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A couple of Masterton District Council officers have designed and built a boat to monitor the toxic algae bloom that annually plagues Henley Lake.
The $1000 project was funded through the council’s staff invention fund, with its makers hoping their innovation will assist those using the lake for sport, as well as helping to determine at what point conditions trigger the algae bloom.
The new remote-controlled survey boat was designed and built by MDC’s Geographical Information Systems officer Alan Flynn and technical services officer Ken Downing.
Mr Flynn said the council tests the edges of the lake, and puts up signs warning humans and domestic animals to steer clear of the water when the bloom reaches a toxic level.
This occurs each year during the warmer months, usually from January to March.
However, Mr Flynn said this was the prime time for training for many water sport clubs, such as waka ama and dragon boating, some of which continue to use the lake during this period.
“At the moment we don’t have any quantitative data to support whether they should or shouldn’t be there, and we would like to be able to inform them of the level of the risk that they are exposing themselves to.
“We want to build up a body of data over the years so that we can actually quantify that and give them informative information to say ‘yes you can be there, although there is this much level of risk’, or ‘hey you really shouldn’t be there — the level has reached a point where it is toxic to humans and our advice is to stop for a time’.
“Hopefully we will have a better picture at the end of the testing.”
The boat, weighing about 30 kilograms, is controlled from land by a radio control unit.
It will collect weekly water samples from the lake’s centre, which will be sent to Nelson and analysed at the Cawthron Institute.
The boat also has a GoPro camera mount allowing video footage to be taken above and below the water.
Its hull is made out of offcuts of plastic piping, and the Wairarapa Resource Centre donated the bearings and shaft for the rudder. Mr Downing built the electronic circuit for the rudder and motor control.
The degree of toxicity in the lake each year is partly determined by water temperature and river flow into the lake.
“If you get a good volume of water going in, the time the lake is closed is a shorter period.”
Mr Downing said the lake had seen good water flow this year.
