The council is placing the buoys in locations with depths of about 350m in Lake Wakatipu and 220m in Lake Wanaka, understood to be deepest-tethered freshwater quality monitoring buoys in the country, council lake scientist Hugo Borges says.
"They’ll become a key part of our overall lakes monitoring programmes focused on monitoring water quality," he said.
The buoys, manufactured in Cambridge by Limnotrack Ltd, operate entirely remotely and will transmit data to council databases in near real time.
Parameters measured throughout the water column, from the surface to 120m depth, include water oxygen levels, phytoplankton (algal) growth, water temperature, conductivity and lake water clarity.
An additional oxygen and temperature sensor will also be deployed near the lake bed from which data will be collected periodically.
Mr Borges said the valuable data set would allow ORC scientists to monitor changes in the water over time, including plumes during storm events.
Once in place, the public will be able to access the data, as will universities, environmental organisations and lake managers researching waterway projects.
Of likely high interest to the public will be relaying of near real-time weather conditions from a meteorological station on each buoy. The buoys weigh 120kg-150kg each and are 1200mm in diameter by about the same height; above the water.
"The chosen sites in these nationally significant water bodies will provide us with baseline monitoring, to assess changes in the lakes due to climate change, or other factors such as catchment development."
The regional council has a 35-year resource consent from the Queenstown Lakes District Council for the buoys and moorings along with licences from Land Information New Zealand for use of the lake beds.
The three-point mooring system has been designed by Christchurch engineering company Offshore and Coastal Engineering Ltd, which specialises in deep-water mooring systems.
It is recommended all watercraft stay at least 50m away from the monitoring and marker buoys, to avoid any disturbance of the mooring system.
Each of the mooring systems and monitoring buoys will be put in place over one to two days, depending on lake and weather conditions, using three craft.
The regional council has a Limnotrack buoy in place on Lake Hayes, at a depth of 30m, which has been operating since July 2019.
At least one more buoy is being considered for deployment on Lake Hawea, during the 2022-23 financial year.
Despite the fully autonomous operation of the buoy system, they require regular maintenance and verification of the data through comparison with manually collected and laboratory-analysed samples.
The two new buoys are being leased from Limnotrack for the first two years, which includes technical support, and Mr Borges said this arrangement might be reviewed in the future.
