Toop said, "twelve brave New Zealanders took a stand today" on behalf of "all" who wanted to save New Zealand's rivers, land, and climate from industrial dairy expansion.
Greenpeace said the Mackenzie is home to the endangered native kakī/black stilt and claims it is not suitable for dairy farming.
The Mackenzie is a naturally dry region. Greenpeace said its soils are characterised as well-drained, or "leaky", which means agricultural pollution could easily leach into waterways.
The proposed new dairy farm, owned by Dunedin accountant Murray Valentine, has almost all the consents and permissions it needs to go ahead.
The Government is rewriting the regulations around freshwater and agricultural pollution. That's due to be released later this year.
Nearly 30,000 people have signed the new Greenpeace petition to ban new dairy conversions across New Zealand.