Council has begun planning a monitoring programme at Lake Hood to better understand the water temperature and level of dissolved oxygen in two areas of the lake.

The monitoring will start in September and the data will help create a base line of lake conditions that will assist scientists looking at ways to inhibit the growth of cyanobacteria in the lake next summer.

Cyanobacteria blooms in warm temperatures and the algae reduces dissolved oxygen when it sinks and decomposes.

Group Manager of Infrastructure and Open Spaces Neil McCann said Council staff were already regularly meeting with Professor Susie Wood from Lincoln University, and scientists from the National Institute of Water and Atmosphere (NIWA), and sharing information about the lake.

“We’re also going to create a hydrodynamic model of the lake to simulate water circulation patterns, which are key to understanding how nutrients move about the lake and settle, and then contribute to the algae blooms.”

Health New Zealand last week lifted its health warning for Lake Hood, which had been in place since March because of levels of potentially toxic cyanobacteria.

Mr McCann said that the university scientists will also help Council consider different products that could be trialled in the lake and canals to mitigate the further development of algal blooms.

“One of these is a sonar solution, which would use pressure waves to break the algae cells and inhibit their growth. There have been many other solutions suggested but we need to determine a cost effective product that will be suitable for Lake Hood.

“We have to figure out a long-term way of managing or inhibiting the growth of the cyanobacteria when the weather gets warm and it’s not as simple as flushing the lake, because we don’t typically have access to much water from the Ashburton River during the drier summer months.”

Mr McCann will also be talking to lake residents at the annual meeting of the Huntington Park Property Owners Association on 7 August.

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