Central Otago Environmental Society member Phil Murray raised the group’s concern about a proposal for the council to present a local Bill to Parliament to rebuild and expand Falls Dam.
"Water quality in the Manuherikia catchment has been declining over the past decade and longer, in line with a quite rapid and significant land use facilitated by water extraction from the catchment."
The group accepted the dam had to be replaced but it did not agree that a new one should be three times the size, he said.
It was hard to understand the justification for building a larger dam using ratepayers’ and taxpayers’ money.
"Where is the benefit to the wider community when the unavoidable consequences of such a dam will be an acceleration of the decline in water quality and ecological health of the Manuherikia and its tributaries?"
A larger dam would result in more than doubling the irrigated land area, most likely into pasture and pasture feed crops, supporting dairying, Mr Murray said.
There was no comprehensive minimum flow for the catchment and no restriction on winter feed crops being established on highly porous alluvial soils near the river.
The group’s fear was the Manuherikia River would end up in the same poor state as those in Southland and Canterbury, he said.
Subsidising irrigation in Central Otago was an attempt to facilitate land use better suited to areas with higher rainfall, such as Southland and the Waikato.
The Manuherikia irrigation scheme was a result of economics distorted by a government subsidy when it was originally established, Mr Murray said.
The proposal was taking the decision about the future of Falls Dam out of the local community.
Maniototo councillor Stu Duncan said irrigation users across the district ranged from farmers to lifestyle block owners.
Much of Central Otago’s growth and productivity was from farming and that needed water.
An enhanced Falls Dam could enhance tourism and attract new events such as rowing regattas, he said.
Central Otago District Mayor Tamah Alley reiterated no decision had been made on whether the local Bill proposal would go ahead.
