Six shipping containers have been placed in the canals at Ashburton’s popular Lake Hood to be used in water quality trials.
The district council is trialling treatment options to stave off algae blooms that have plagued the lake over the last three summers.
The containers have been placed to create a controlled area in part of a canal along Huntingdon Ave, to test five different applications.
Other areas of the lake will be used to monitor three different types of sonic equipment.
The data collection and monitoring will be led by a team from Lincoln University.
Infrastructure group manager Neil McCann said scientists would be onsite this week to begin testing a range of algal-control products targeting cyanobacteria.
“The aim of this work is to test the setup for four weeks, and prepare for a more scientific trial to be undertaken in February and March when cyanobacteria levels are expected to be higher,’’ McCann said.
“One of the containers will be an untreated control container, and the other five will be used for testing three chemical and two biological products.”
The shipping containers have had their tops and bottoms removed and are mostly submerged in the canal in a section near the pedestrian bridge.
Scientists will be monitoring cyanobacteria, chlorophyll-a, total N, total P, H, dissolved oxygen, turbidity and temperature, he said.
“We would prefer people on the water in the canals to keep away from the test zone for the four-week period in November, and scientists and helpers will be coming and going during the course of the trial.”
The weed harvester has begun its regular patrols, cutting and removing weed as required.
Environment Canterbury is set to begin its annual monitoring of swimming and water recreation sites, including Lake Hood, this week.
Last summer, the testing regime resulted in a health warning being placed on the lake, for a third straight summer, on March 20, but not before two people were recorded as being poisoned by the toxic algae.
In response to the public health risk, the district council closed the lake from April 3 until June 19, while the health warning wasn’t lifted until July 4.
The district council considered a 75-page report on the water quality issues at Lake Hood and the options to address them at a workshop on May 21.
At that meeting, chief executive Hamish Riach said the district council had called in the leading cyanobacteria scientist in New Zealand, Lincoln University-based Professor Susie Wood, to lead the investigative work towards a solution.
Scientists from Earth Sciences New Zealand (formerly NIWA) are also assisting the trials.
