The Pickering Road pond, created as part of the Waikato Expressway, is set to become a local environmental feature.
Eventually it will be surrounded by 10,000 plants and is already being used by birds and frogs, which have returned as pond insects provide a food source.
Rare native bats, too, have been found to be living in the area.
The pond serves to collect and treat water from the expressway but also provides important ecological support for the surrounding area.
Planting around the pond will include plants which act as natural water filters.