A Waiau Trust in Southland is 20 years into its work with farmers to create and protect wetlands and waterways.
Waiau Fisheries and Wildlife Habitat Enhancement Trust was set up in 1997 by Meridian and the local community to reduce the effects of the Manapouri power scheme.
The trust provides grants to landowners - including private farmers and Landcorp - to fence streams and wetlands.
It has developed 180 projects over its 20 years.
Trust chair Cam McCulloch said one of the largest projects was around protecting whitebait habitats.
"Recent academic studies have indicated that whitebait populations are declining. We've been working in this area now since 1999 and we've established about a 30-hectare area of enhanced habitat.
"If a species doesn't have a habitat it can't survive, we can see other areas at the mouth of the Waiau which could be developed as well ... so we see that as being particularly important."
The projects have not been without their challenges.
"It's something that hasn't been done to a great extent in the past so we've had to learn a lot as we go along.
"The other challenge is the river flow goes up and down so there can be periods where the flow is quite low, and we've got to work out ways of ensuring the area doesn't get de-watered during those low periods."
Mr McCulloch said at the other end of the scale, the Waiau River had sometimes flooded and washed their work away.