Ashburton District Council is proposing to create a dedicated Lake Hood Manager role as part of its draft 2026/27 Annual Plan, reflecting the scale of work required to secure the lake’s long-term future.

The proposed position would oversee water quality mitigation, resource consent renewals, strategic planning for the lake and its surrounds, as well as scoping and contract management.

Key consents for the lake are due to expire by 2031, and Council says preparation will need to begin well in advance in an increasingly constrained regulatory environment.

The confirmation of this position is still subject to further scrutiny through the draft Annual Plan process before it is confirmed.

Group Manager of Infrastructure Neil McCann said learning from current research and hydrodynamic modelling would be vital to supporting future consent applications.

“What is critical is to learn from the research and hydrodynamic modelling to start preparing for the consent applications,” he said.

Research update to property owners

An update on that research was provided to residents last week at a special general meeting of the Huntingdon Park Property Owners Association, where Professor Susie Wood outlined progress on water quality trials and the complexity of the issues facing the lake.

Professor Wood said that when she first became involved in the project, she expected poor circulation to be the primary cause of the lake’s problems.

However, research has since revealed a much more complex picture.

“Our research is focusing on two key aspects. First, we are trying to understand why the blooms are forming.

"Currently, we think that in addition to water circulation, pulses of nutrients entering the lake from the river and sediments, along with fish that alter the lake’s food webs, are all contributing,” she said.

“In the second part of our research, we are exploring whether chemical and biological products can help in the short term.

"Our idea is that these might be applied in specific locations, particularly when blooms are just beginning, to reduce their intensity.

"These products will not fix the underlying problem, but they may help while we work towards longer-term solutions.”

Around 20 companies approached the Council with potential solutions.

Working alongside Council staff, Professor Wood helped shortlist five products for further investigation.

The team is now testing these products in ‘mini lakes’ set up in one of the canals.

These systems simulate lake conditions while isolating the products from the rest of the lake.

The trial has been underway for over three weeks now and will run until the end of April.

In addition, three ultrasonic units have been installed in the lake.

These use high-frequency sound waves to control algae, and the team is undertaking extensive monitoring to determine whether this could be an effective solution.

“There are many potential solutions for the lake.

"The residents and council have been great to work with, and because of their intimate knowledge of the lake, they have many excellent ideas that will likely contribute to a multi-tiered solution,” Professor Wood said.

“It’s crucial that we understand why the blooms are forming so that we can ensure the resources, both time and money, we invest in solutions that deliver the best possible outcomes.”

Recent sampling

The most recent cyanobacteria sampling result from 12 February was 0.3mm3/L and was taken from the water ski area.

Two consecutive results below 0.5mm3/L are required before Health New Zealand will consider lifting the public health warning.