About 200 gathered at lunchtime to tell the council what they thought about its record and asked for more of a say on the granting of irrigation consents.
Among the protesters' concerns was the granting of another 10-year consent for the Mayfield Hinds Valletta irrigation scheme in mid-Canterbury.
They said it was a free pass for dairy farmers to continue producing polluting nitrates, mostly from the urine their cows produced.
"The Hinds River is in a pretty terrible state. You can hardly even call it a river any more. For that river it's diabolical."
To be granted consent, the 200 farmers had to agree to reduce nitrates by 15 percent by 2025 and by 25 percent by 2030.
But Snoyink said the water was so degraded that even reductions of this magnitude were not enough to make a real difference.
She noted the target the farmers were aiming for, of 6.9 milligrams of nitrate per litre of water, was almost three times the amount recommended by the Ministry for the Environment to maintain healthy waterways.
"I think they have to do more because the limits that they have actually set in the plan for water is not an ecological limit, all the native species pretty much die when the limit's one milligram [nitrate/l water]. So it doesn't give me confidence at all that it's going to clean up our waterways anytime soon."
Extinction Rebellion spokesperson Siana Fitzjohn said the only way to turn the nitrate ship around was to drastically reduce herd numbers.
"The reductions are big, but it's up to the whole community to help farmers make that change. And it's also up to the government and to regional councils to help facilitate that diversification of land use and to support farmers in that transition. And so we're not saying that the onus needs to be on farmers alone."
One of its members, Gen de Spa, said the council needed to promote regenerative farming as a way to reduce polluting nitrates.
"For many years, we've been trying to maintain this precarious and unlikely balance between the economy and the environment. And I think that is really a ridiculous idea. What we need to be thinking about is alignment between the economy and the environment."
Environment Canterbury chair Jenny Hughey addressed protesters, thanked them and said their actions helped to put pressure on the council to do more to protect people's water.
