"It is our mataitai - where we gather food - and we are renowned at the marae for providing good seafood for tangis and events.
"It was clear if contaminants got into the river they would flow to the sea."
So she "had a good think about it" and then began making the calls and the approaches - to fellow locals and to the Wairoa District Council and the Hawke's Bay Regional Council.
The wheels of "we don't want that to happen" began to turn.
She started the restoration of the Whangawehi water project on her own, but gradually the support grew and so did the determination to achieve a result.
Her first task was to convince her own people they could make a change - make a difference - but it wasn't easy.
"Some laughed and said it couldn't be done."
A year of hui and meetings and consultations followed to convince others to become pro-active rather than reactive.
She and the group gained traction and a major milestone was reached in July 2011 by the first signing of a memorandum of understanding among three marae, the Hawke's Bay Regional Council and the Wairoa District Council.
It was followed by a second signing early in 2012.
They were the first steps towards what is now the Whangawehi Catchment Management Group - a unified body of stakeholders including marae, agencies and school representatives, working together to better manage land and water in the catchment and also co-ordinate environmental work and education in the community.
Shortly after the second signing, Kathleen organised hui and forums to develop what is now a driving document - a community-led Catchment Management Plan which clearly identifies priorities and work to be done. The key objective has been improving the cultural, ecological, economical and recreational values of the Whangawehi catchment with a clear focus on improving water quality and the habitat for freshwater and estuarine species.
"Our mission statement is, 'The river is sacred to us and we want to see the kaimoana come back and sustain us again'."
While the wastewater ponds had gone ahead the changes were significant.
"We planted trees around the site and the water from the ponds does not go into the river - it is sprayed on the trees and they soak it up - we insisted it be done that way."
Clean waterways and the planting of native trees was what she called a "devotion and real passion".
She added it was good to be recognised, although she had never sought it.
For more information on the award, visit prideofnzawards.co.nz