Swimming hopes buoyant amid Lake Rotoroa clean-up bid
Thursday, 29 January 2026
The dream of taking a summertime dip in Hamilton’s Lake Rotoroa isn’t dead, with new plans to be considered Thursday floated to help improve water quality.
The lake is currently at a ‘caution’ level, meaning people should avoid the water — something they have been advised to do for decades.
Members of advocacy group Whakamana ki Rotoroa will meet with Hamilton City Council staff in a bid to improve water quality at the popular recreational site.
Ideas include planting in and around the lake — and even, with a floating wetland — planting on it.
The group is hoping to secure funding from a kitty of about $480,000 previously tagged to the development of wetlands that were found to be non-viable.
Whakamana ki Rotoroa spokesperson and Hamilton City Councillor Anna Casey-Cox said contrary to public perception, the lake was already among the cleanest peat lakes in the Waikato region.
“It will take some investment…but it’s not that far off, and we can’t give up on water.”
“We want to be able to swim in our local lake — that's the vision and the hope.”
The group was keen to carry out more planting in and around the shallows of the lake to help absorb contaminants.
In addition, the group was advocating for the creation of a floating wetland – a platform of wetland plants sitting on the surface of the water.
It would need to cover at least 5% of the lake to impact water quality.
While the concept was still under development, the group believed it would be an effective strategy that, topped with an art installation, would also inspire people.
Artist Lynette Wilson created a design evoking the play equipment she recalled from summers swimming at the lake as a child.
“There was a slide that used to go into the lake — it was very popular amongst us kids,” Wilson said.
It was removed in the 1980s, after people became aware the once “pristine” lake was no longer safe.
Whakamana ki Rotoroa was also initiating research in partnership with the University of Waikato, examining the feeding patterns of waterfowl, as the birds had a direct impact on bacteria levels in the lake.
Casey-Cox said they aimed to begin this summer, with meetings already underway between the group and council staff to explore how the study could be carried out.
“It's looking at whether there could be some deterrents put in place, to encourage ducks out of a particular spot, so that it then could become more of a swimming area.”
They were keen to see more city council funding made available for the lake, she said.
About $600,000 had been budgeted for water quality infrastructure in the current long-term plan, with the intention of developing wetlands that were then found to be non-viable.
About $480,000 remained after funding lake monitoring and other equipment, she said.
“We're hopeful that that budget will go towards what it was originally intended for, which was more along the lines of the wetland approach.”
“The land around the lake may not be able to be used for wetlands, but you can certainly do things on the margins and in the lake that may be effective.”
If funding was allocated towards a floating wetland, this would not be used to cover the proposed art instillation, she noted.
Whakamana ki Rotoroa also called for a lake restoration strategy setting out the roles of the multiple agencies, including Hamilton City Council, Waikato Regional Council, the Waikato River Authority, and philanthropic trusts.
In January 2025, the city council installed a high-tech monitoring system to keep tabs on the lake’s health, tracking everything from water temperature to nutrient levels.
Casey-Cox said this was positive and should continue, but there was already a decent amount of information available.
“We know quite a bit now. It’s time to take action.”
The city and regional council both emphasised a collaborative approach, but warned improvements in water quality took time to achieve.
Hamilton City Council Parks & Recreation Unit Director Maria Barrie said the monitoring programme would run for 24 months, and was now at the halfway point.
The data was improving their understanding of the factors affecting water quality, although there was “no single solution”.
People could help by picking up litter, not feeding ducks bread, joining planting events, or reporting issues, she said.
Waikato Regional Council senior water scientist Mafalda Baptista said many lakes in the region were hazardous to swimmers because of high levels of nitrogen and phosphorus from rural and urban run-off and sedimentation.
This, combined with warm summer days, caused harmful cyanobacteria — or blue-green algae — to bloom.
The regional council monitored 38 lakes and led initiatives to improve water quality.
While many lakes were degrading, others such as Lake Whangapē seemed to be improving.