The Maitai is the country's second most improved river.
The Nelson river was awarded runner-up for most improved river across the country and most improved river in Nelson at the New Zealand River Awards in Wellington last week.
The awards, organised by the New Zealand Rivers Trust and Morgan Foundation, focused on improvements in the river's macroinvertebrate community index.
The Nelson City Council began improvements on the river in July 2014 with a four-year, $400,000 Project Maitai/Mahitahi after identifying the river's declining health.
Community action group Friends of the Maitai was coincidentally established at the same time with a focus to work alongside the council and other groups help to restore the river.
The awards indicated the Maitai River had seen an expansion of riparian planting, reduced levels of exotic forest harvesting and positive changes to reservoir management.
One of the Friends of the Maitai's founding members Tom Kennedy said the group formed after its concerns of rising levels of cyanobacteria, commonly known as blue-green algae, in the Maitai.
He said while its actions had been small it was positive to see any change in the river's health which he hoped would continue.
"It was almost a perfect storm ... the council-run project, plus the group that came out of that initial meeting and the public awareness and the media coverage was really good."
A number of interest groups were formed to monitor the river, re-plant natives and work with forestry.
Kennedy said the group weeded an area near Groom Creek, opposite the Maitai Valley Motor Camp, every fortnight to help the council's vision to create a "green corridor".
He said one of the main reasons native planting was so important was to keep the river's temperature down to keep fish alive and "hold back a lot of sediment that comes off the hills".
"That's where with the forestry we have been working quite diligently with those groups. That's been quite difficult until recently ... they've been quite proactive."
He said the macroinvertebrate improvement over the past two years was a good sign but there was still a long way to go.
"It's a good result but as far as anything that we've done ... I can't imagine it's had a huge impact upstream where the council as been monitoring."
He said the health of the river was hugely important to have a healthy, continuous ecosystem in Nelson.
Kennedy said the council had also created a wetland adjacent to the Groom Creek planting area.
Mayor Rachel Reese said the groups and the council had worked together to take "huge steps" toward the restoration and protection of Maitai.
"The Maitai/Mahitahi is important to each and every one of us as a source of water," she said.
"We will continue to work to protect the Maitai/Mahitahi for the benefit of those that enjoy it today, and for generations to come."