A bat survey, buffer planting and weed and pest control measures have been suggested to mitigate the ecological effects of the Ruataniwha Water Storage Project.
A two-year bat population survey was suggested before construction, and other measures included the planting of a buffer around a large portion of the dam reservoir where stock grazing was likely to occur and restoration of habitats on private land upstream of the dam reservoir.
Pest and weed control measures were also suggested. The report suggests they could be enforced using consent conditions.
If undertaken they would contribute to 146ha of habitat recreation and enhancement around the new reservoir and within its sub-catchment, animal pest control over 616ha of bush, scrub and wetland, and approximately 314ha of braided river habitat.
The Kessels and Associates Ltd report surveyed ecological populations in the area and the anticipated effects of the dam on their habitats. It is only one of a number of reports detailing environmental, cultural, and technical aspects of the project.
Field assessments were undertaken from the six months from September 2011-February 2012 across areas that would be affected by the dam. The total area to be affected by flooding, the dam structure and spoil disposal was approximately 450ha.
The resident bat population was expected to be negatively impacted, with a suspected roosting site located in the dam area.
"Thus, the results of the bat surveys suggest that the loss, modification or disturbance of the habitat within, and surrounding, the proposed reservoir and dam could have a significant negative effect on long-tailed bats within the locality," the report said.
Bird species would also be affected, but the report said this could be alleviated.
"Potential adverse effects on the bird species found within the proposed reservoir and dam footprint can be adequately mitigated by appropriate habitat restoration and enhancement," the report said.
"It also should be acknowledged that the new lake and its edges will provide new habitat for existing and presently less commonly occurring birds, such as shags and dabchick."
The field surveys only found one gecko within the area, which was considered surprisingly low.
The effects of the dam on lizard populations was expected to be minor but it was suggested another survey should be undertaken. The effect on invertebrates was expected to be minor because of suitable surrounding habitats, but the transfer of top soil before flooding would save populations, as would the pest control measures suggested.