Munro said the council was navigating a time of significant change, including determining how to implement the Government’s Local Water Done Well reforms.
She said she would not be seeking re-election in October.
“Given the uncertainty surrounding my health, I cannot fully commit to serving our community in the years ahead,” she said.
Munro served two terms as a councillor from October 2016 before being elected mayor in 2022.
She was diagnosed with cancer shortly before Christmas last year.
Deputy Mayor Karen Morgan would continue acting in the top role until the election, she said.
Munro said Morgan had led with “calm and capable hands” in her absence.
Munro thanked council management and staff for their “expertise, dedication and adaptability”.
“Without your efforts, many of us would have no water in our taps, no roads to drive on and no shared community spaces to enjoy. Few outside the organisation truly appreciate the breadth and complexity of the responsibilities council carries every day,” she said.
She thanked her fellow elected members for their “time, energy and unwavering commitment” to the community.
“Your insight and shared purpose have helped keep council focused on what matters most,” she said.
Munro also thanked the residents and ratepayers whose support “meant so much”.
“Needless to say, this is not where I expected to be, nor how I imagined my time in local government would come to an end. But perhaps it’s a reminder that change is life’s only constant. We can’t always control what comes our way, but we can choose how we respond,” she said.
“Politics, even at the local level, can at times be divisive. My hope is that, as a community, we continue to meet challenges with open minds, respectful debate focused on the issues not the individuals and a spirit that celebrates both our differences and the values we share.”