Six shipping containers that have been helping scientists prepare for an algal-control trial in Lake Hood will be removed on 18 December, as the first phase of work comes to an end.

The containers have been sitting in a canal alongside Huntingdon Avenue and will be craned out and stored at the lake’s maintenance depot, where they will be jetwashed in readiness for the next phase of the trial.

Group Manager of Infrastructure Neil McCann said the cleaned shipping containers would be put back into the canal on 19 January.

“The preliminary run has taught us a lot about the conditions, testing environment and the site set up, which has helped us plan for the scientific trials to start in February, which will involve a lot more testing and monitoring.

“We’ll be trialling the same five algal-control products plus one control container, and also installing sonic equipment in three other spots in the canals to see how they can mitigate the growth of cyanobacteria.”

The shipping containers will remain for up to three months as the different products are tested thoroughly over time.

The sonic treatment involves floating devices that use sound waves to break down the cyanobacteria cells.

Mr McCann said the scientists would be on site more regularly during phase two of the work.

“This will be an interesting part of the trial and it’s crucial the science team gathers as much information as they can, because their work will help us decide on the best way to manage Lake Hood going forward.

“We will continue to harvest lake weed this summer and circulate as much water as we can through the lake and canals to help control the cyanobacteria levels, but we are up against nature.”

Environment Canterbury has begun its summer testing of contact recreation swimming sites and the sample from Lake Hood on 28 November returned a result of 0.03mm3/L biovolume of cyanobacteria. This means the lake is in a green surveillance mode.

Council is also monitoring water quality at 10 other sites at the lake, using a hand-held cyanofluor device, which gives an indication of cyanobacteria levels.

Mr McCann said all the information helps Council manage the lake, which is a popular spot for residents and visitors year-round.

“We’ll be continuing our regular water quality updates for the community through summer and sharing information about any other work that happens there.”

Council has a dedicated Lake Hood page on its website, ashburtondc.govt.nz