"This could be one of the greatest savings of fish we've seen in my lifetime," Mr Hansen said.

"It's effectively like putting the money and effort we've put into restocking, but 50 times over."

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Hansen described the program, and the alliance of environmental interests, the Department of Primary Industries and irrigators as a 'massive win' for the waterways.

"It's great to see that native fish will no longer be transferred out of the river and deemed lost, now they'll remain in river to breed naturally," Mr Hansen said.

"It's great for jobs, it's great for growth, it's great for regional economies and, from our perspective, it's great for fish."

Mr Hansen said that traditional methods of protecting and increasing the numbers of native fish, like restocking, paled in comparison to the numbers that could be saved by stopping the accidental extraction of fish.

"Restocking really is just a band-aid solution," Mr Hansen said.

"It's like trying to re-populate a town through IVF, it works in some instances where there are no fish, but it really is more cost effective to have fish in the river, laying tens of thousands of their own eggs rather than the taxpayer forking out a dollar for each fish."

"Stocking two to three million while you suck 50 to 100 million out, it's a no brainer that makes no sense at all."

While environmental groups and recreational fishing proponents have often sparred with irrigators in the past, Mr Hansen praised the Trangie-Nevertire Irrigation Scheme members for coming on board with the project.

"The TNIS has now set the standard for best practice in water extraction, not only in the Macquarie valley, not only in NSW, but right across the country," Mr Hansen said.

"They've won numerous awards for bettering their practices in the past and now that they have those fish screens going in and partnering with the community and the rec fishers and government and now this milestone project is going to set the benchmark."

Mr Hansen said the project's long shelf-life, having been developed over decades after seeing how similar projects had become the standard in North America for a long time as a matter of legislation, was necessary to match the magnitude of the problems the ecosystem faces.

"It's been a very tough time for native fish, we've had catastrophic fish kills in this valley, we've had fish older than me, older than 40 years old dying and that's a very hard thing to face, you can't just replace those fish overnight," Mr Hansen said.