Ngai Tahu's plans to put intensive irrigated dairying on Balmoral forest could see about 20,000 cows farmed on land on the scenic commute to Hanmer.
Plans for the area will be the first heard under the new Canterbury water plans introduced by Environment Canterbury (ECan) commissioners.
The Hurunui and Waiau River Regional Plan became operational in December - the first in the Canterbury Water Management Strategy and the 10-zoned committee structure.
Submissions closed yesterday and there are already concerns Ngai Tahu's resource consent will immediately prove the plan inadequate.
The plan sets a nitrogen limit in the Hurunui catchment which allows for more development but only if the phosphorous levels remain at a status quo.
Ngai Tahu Forest Estates wants to transform Balmoral by introducing 5000 hectares of irrigated dairying, 617ha of dryland farming, 1120ha of irrigated wintering and 979ha in native.
Former ECan councillor and Cheviot resident Jane Demeter said people were concerned.
"This is a river under stress from current farming - in the past year for swimming and recreational the water quality has already dropped from fair to poor [rating]. In the lower reaches we cannot swim, recreate [or] fish in it because of the presence of blue-green algae blooms," she said.
Hurunui has the highest number of cows to hectares in New Zealand at 3.68.
Hurunui-Waiau zone committee chairman David Eder said the phosphorous levels were already higher than accepted levels at the State Highway 1 section of the river.
"With the phosphorus level already over there, really in practice no-one can allow further development there. Ngai Tahu's will be the first to test this [the plan]," he said.
Forest and Bird field officer Jen Miller and Fish and Game adviser Scott Pearson said they had opposed the consent.
Ngai Tahu did not respond to a request for comment.
- Fairfax Media