The group of about 20 spent the day clearing alligator weed and planting items donated by the public.
Once the stream's edge was cleared of weed, the group planted harakeke there, which helped protect and clean the stream.
"Harakeke is versatile and it acts as a sponge, as a filter. Even if it does flood, it won't die," Ms Tangaroa said. "We've got some native seedlings as well."
The work at Kokohuia would continue regularly, she said.
"In future ones we'll be working right up to the fence line. We're going to plant this whole zone eventually."
She hoped birds and insects would return to the area. "We hope that one day this area will be a testament to the community."
The work was being done without weedkillers and Ms Tanagroa wanted to use it as an example of how weed control could be done without puting toxins into waterways.
Fresh water was one of her passions and it kept her motivated to run projects such as the Kokohuia rejuvenation.
"I'm from the river," she said. "I've lived the majority of my life on waterways. Wherever I've lived I've always been passionate about waterways. I'm just connected. The water speaks to me."