The project area supports a variety of natural settings and landscape features that provide habitat for native flora and fauna including escarpments, ravines, rivers, creeks and reservoirs. There has been significant effort to identify the biodiversity values within the Exploratory Works survey area, and design the works to avoid and minimise impacts to the identified values.
Desktop assessments, mapping and field surveys have been used to assess the biodiversity values and threatened species in line with State and Commonwealth legislation and guidelines. Native vegetation condition within the project area reflects evidence of past land use, including clearing and ground disturbance, and also contains areas of undisturbed land and important habitat. Where possible, works have been limited to previously disturbed land.
Field surveys suggest that Exploratory Works will impact the habitat of some threatened fauna including the Gang-gang Cockatoo, Eastern Pygmy-possum, Booroolong Frog (within and along Yarrangobilly River), Smoky Mouse and Masked Owl. Talbingo Reservoir and the Yarrangobilly River were identified as potential habitat for threatened aquatic species including Murray Crayfish (found during surveys), and Trout Cod and Macquarie Perch (not found during surveys). There are no threatened plant species identified in the project area.
Impacts to biodiversity are likely to arise in two ways; from direct impacts by clearing of vegetation or habitat during construction, and by indirect impacts to habitat such as erosion, sedimentation and changes to water quality, as well as noise and light affecting adjacent natural areas during construction.
The impacts on Smoky Mouse habitat (a critically endangered species in NSW) are potentially the most serious and therefore the works have been designed to ensure that impacts are minimal. No road widening will be carried out in the area of identified habitat, which is primarily limited to the upper section of Lobs Hole Ravine Road. In addition and to avoid and minimise impacts to the Booroolong Frog, Murray Crayfish and potential Macquarie Perch habitat, a 50m exclusion area has been placed around the Yarrangobilly River. This exclusion area was developed in consultation with recognised government species experts, including from NPWS and OEH, as it was determined that if works can be avoided within this buffer, direct impacts to Booroolong Frog and their habitat can be avoided, along with most indirect impacts. The two bridges that cross the Yarrangobilly River and Wallaces Creek will also be designed to avoid impacts to fish passage.
The placement of excavated material in Talbingo Reservoir will be below the minimum operating level and at depths that generally avoids high quality aquatic habitat associated with shallower environments. Displacement of aquatic habitat in Talbingo Reservoir due to dredging and construction of barge access infrastructure and placement of dredged sediment and material excavated from the tunnel would largely be minimised and restricted to soft sediments. This type of habitat is abundant throughout the reservoir and the loss of a very small area is expected to have negligible impacts to aquatic ecology at this scale. Some habitat, such as wood debris, would be relocated to other areas of the reservoir to ensure there is no net-loss of this type of habitat.
Impacts to biodiversity will be avoided and minimised as much as possible, but there will still be some residual impacts and these will need to be offset in line with legislation and through agreement with NPWS and OEH. This includes species and habitat offsets, land, weed and pathogen management, and rehabilitation works. Snowy Hydro has agreed an in-principle approach to offsets with NPWS and OEH, with a key principle of the offsets being of direct benefit to KNP – an approach local stakeholders are very supportive of.