Loss of habitat threat to birds and fish: Inquiry

Massey University ecologist Mike Joy told the inquiry the scheme would impact negatively on the health of the Tukituki River ecosystem. Photo / Duncan Brown

The Royal Forest & Bird Protection Society says the backers of the Ruataniwha dam have not carried out sufficient research to determine the project's impact on threatened plants and animals.

The Ruataniwha Water Storage Scheme, which includes the dam, is being promoted by Hawke's Bay Regional Council and its commercial arm, Hawke's Bay Regional Investment Company as a means of boosting agricultural and horticultural productivity in drought-prone Central Hawke's Bay.

A board of inquiry is under way to determine whether to grant resource consents for the project.

The council is also seeking a related amendment to the Hawke's Bay Regional Resource Management Plan, known as Plan Change 6.

Opening Forest & Bird's submissions at the hearing yesterday, the society's lawyer, Sally Gepp, said it supported Plan Change 6's objectives of setting limits on water quality and allocation in the Tukituki catchment, although it had some concerns about the plan.

Forest & Bird was opposed to the waste storage scheme, however, "on the basis of its effects on water quality through enablement of large-scale land use intensification, aquatic ecology, terrestrial ecology and recreation".

The scheme would result in the direct loss of 243ha of significant indigenous vegetation and habitat, and changes to the downstream habitat of an "internationally important" river bird population and a significant loss of habitat for native fish, including seven at-risk species.

Proposals put forward by the scheme's promoters to mitigate and "offset" the environmental impacts of the project were inadequate, she said.

"The best that can be said of the proposed mitigation and offsetting measures is that they will have a low to moderate degree of success."

An expert witness for the society, Massey University ecologist Mike Joy, told the hearing the water scheme would have a negative impact on the health of the Tukituki River ecosystem.

There would be two types of impact, he said: those resulting from changes in water quality and the effects on native fish.

"There is a clear and obvious relationship between farming intensity and ecological impacts," he said.

Dr Joy also questioned the validity of a scientific model the council has used to predict changes in nitrogen and phosphorus levels across the Tukituki catchment if the dam is built.

The TRIM model, developed by Niwa's principal freshwater scientist, Dr Kit Rutherford, "while conceptually sound suffers from input data of dubious quality".

The council's lawyer, Trevor Robinson, asked Dr Joy to comment on a newspaper report of a talk he had given.

The article reported Dr Joy saying his university position meant he could be more independent than some scientists.

He told the hearing he was not implying scientists from the regional council and Niwa who were involved in producing evidence on the dam could not be independent.