Biodiversity and Aquatic Ecology Assessments
Overview
The biodiversity and aquatic ecology assessments were done under state (NSW) and national environmental guidelines. The aim of these assessments was to identify and describe existing biodiversity, and assess the potential of the presence of threatened species of communities listed under state or federal protection legislation. Further, these assessments identified threats to biodiversity and aquatic ecology created by the Snowy 2.0 Main Works, and formed recommendations on mitigation or avoidance strategies to ameliorate impacts.
Jump to impacts, mitigation, or critique
Biodiversity Assessments
It was found that there were no areas of outstanding biodiversity value under the NSW Biodiversity Conservation Act 2016 (BC Act) within the Main Works area or a 1,500m buffer zone. Some threatened species found within the Main Works area included the Mauve Burr-daisy, Clover Glycine, Kiandra Leek Orchid, Smoky Mouse, Booroolong Frog, Alpine Tree Frog, and She-oak Skink.
Flora
Two endangered flora communities were present within the area, including:
-
the Montane Peatlands and Swamps of the New England Tableland, NSW North Coast, Sydney Basin, South East Corner, South Eastern Highlands, and Australian Alps bioregions
-
Alpine Sphagnum Bogs and Associated Fens
​
Of the 38 Plant Community Types (PCTs) found within the Main Works area and buffer zone, 7 threatened flora species were mapped within the disturbance footprint. These assessments recorded that vegetation depends on altitude. Overall, the area comprises sclerophyll forests with large trees and a shrubby or grassy understorey. Higher areas are dominated by Mountain Gum, Snow Gum, and Alpine Ash, while lower areas are dominated by Broad-leaved Peppermint, Robertson’s Peppermint, and Brittle Gum. The plateau area consists of dry grassy plains comprised of tussock grasses, ringed by grassy woodlands of Black Sallee (Eucalyptus stellulata), and Snow Gum (Eucalyptus pauciflora). Along watercourses, wet grasslands, alpine bogs and fens occur. It was also noted that within many sections of the Main Works survey area, the midstorey and understorey were heavily disturbed by past or current anthropogenic land uses, with significant weed invasion, particularly thickets of Blackberry.
Fauna
Surveys were undertaken for specific threatened animal species who were thought to be potentially present within the Main Works and buffer zone. These included:
-
Diurnal bird species: The Gang-gang Cockatoo, Pink Robin, Little eagle, Square-tailed kite, White-bellied sea eagle, Lantham’s snipe, Rufous fantail, and the Satin Flycatcher.
-
Nocturnal bird species: The Barking owl, Powerful owl, and the Masked owl.
-
Small terrestrial mammal species: The Eastern pygmy possum, Broad-toothed rat, and the Smoky mouse.
-
Large terrestrial mammal species: The Spotted-tailed quoll.
-
Arboreal mammal species: The Koala, Squirrel glider, Brush-tailed phascogale, and the Greater Glider.
-
Microchiropteran bat species (microbats): The Southern myotis.
-
Amphibian species: The Booroolong frog, Alpine tree frog, and the Northern corroboree frog.
-
Reptile species: The Alpine she-oak skink.
-
Of these, the Latham’s Snipe, Gang-gang Cockatoo, Little Eagle, Masked Owl, Satin Flycatcher, Square-tailed Kite, White-bellied Sea-Eagle, Broad-toothed Rat, Eastern Pygmy-possum, Smoky Mouse, Spotted-tailed Quoll, Alpine Tree Frog, Booroolong Frog, Alpine She-oak Skink, were recorded within or adjacent to the Main Works disturbance footprint.
Additional non-target threatened species were also present, including the Brown Treecreeper, Diamond Firetail, Dusky Woodswallow, Flame Robin, Olive Whistler, Scarlet Robin, and Varied Sittella were also present.
Impacts on biodiversity
The primary impacts of the Snowy 2.0 project are the clearing of threatened native vegetation and the destruction of high-quality threatened species habitat. This clearing could also result in degradation or fragmentation of habitat for native species, reducing movement, behaviour, and gene flow, and could potentially impact survival. It could also increase the vulnerability of native species to extinction, as populations would be isolated and more susceptible to stochastic local extinction events.
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
Air, light, and noise pollution are additional potential impacts on flora and fauna. Increased level of local noise and vibration, which may impact calling behaviour and movement of fauna. However, as operational noise is predicted to be ‘minimal’, or below 45dB, and only limited to underground particular areas on the surface, the impact of increased noise and vibration is said to be low. Increased dust levels from operational activities and movement of soil and rocks, which may inhibit plant growth and photosynthesis. Increased level of light pollution during night works may also cause additional disturbance to nocturnal species, such as insects, bats and other nocturnal mammals, and owls. Finally, the accidental release of chemicals from construction and human activities, such as fuels, hydrocarbons, heavy metals, sewage, may affect toxicology of the environment surrounding the Main Works site, roadways, temporary housing facilities, and operational infrastructure, affecting flora and fauna.
​
The potential of introducing exotic species into the area is also of concern. An increase in weeds and pathogens, such as African Lovegrass (Eragrostis curvula), that may be transported to the site via equipment, clothing, machinery, and vehicles. Additionally, increased human presence may cause an increase in predatory and pest species, such as feral cats (Felis catus) and red fox (Vulpes vulpes) that prey on terrestrial animals and birds.
​
Increased local traffic could lead to increased vehicle strikes and fauna mortality.
Methods
24,282 records were taken during surveys to record the presence of threatened flora and fauna species. Flora communities were described through mapping extensive survey transects, covering 36,461 ha within the 37,559 ha buffer and Main Works area, and recording species present. For fauna communities, to record potential breeding habitat, behaviour, and how commonly the species was found, targeted surveys were undertaken for:
-
Diurnal birds through targeted nest surveys and transect/area searches
-
Nocturnal birds through call playback and spotlighting
-
Small terrestrial mammals through trapping, remote cameras, and regional surveys
-
Large terrestrial mammals through trapping, spotlighting, regularised grid-based spot assessment technique, and acoustic recorders
-
Microchiropteran bats (microbats) through acoustic detection
-
Amphibians through habitat assessment, nocturnal searches, egg mass and tadpole sampling surveys, and diurnal call surveys
-
Reptiles through tile grids and tile transects
​
To assess aquatic species present, field observations, GSI development, eDNA, egg searches, and the appearance of larvae/growth of cohort, was used to quantify the presence of fish, aquatic invertebrate, and stygofauna.
Many of these surveys and research techniques were undertaken independently by external scientific organisations and universities, with funding from Snowy Hydro Limited.
Aquatic Ecology Assessments
The Snowy 2.0 project is situated within the Murrumbidgee catchment, with some areas also extending into the Snowy catchment.
As a hydroelectric project, is likely to influence the aquatic ecology of nearby water bodies, including the Yarrangobilly River and Wallace’s creek which are connected to the Talbingo Dam, and the Eucumbene River, Murrumbidgee River, Gooandra Creek, Tantangara Creek and Nungar Creek which are connected to the Tantangara Dam. It was also reported that this project will impact groundwater levels and ecology.
Most of these rivers create seasonal ponds and creeks. Vegetation surrounding most of these water bodies are wet grasslands or alpine bogs and fens, however, some sections are heavily infested by weeds such as Blackberry.
In the assessment, it was established that these riparian areas are habitat for aquatic and semi-aquatic species, and are used by birds and bats for more efficient movement.
Riparian Flora
This assessment recorded 3 Plant Community Types (PCTs) that had an obligate dependence on groundwater and would subsequently be affected by the Main Works, including:
-
Alpine and sub-alpine peatlands, damp herbfields and fens, South Eastern Highlands Bioregion and Australian Alps Bioregion
-
Carex - Juncus sedgeland/wet grassland of the South Eastern Highlands Bioregion
-
Sub-alpine grasslands of valley floors, southern South Eastern Highlands Bioregion and Australian Alps Bioregion
Sub-alpine grasslands in Kosciusko National Park
Aquatic fauna
Threatened aquatic species found within the Talbingo and Tantangara dams and associated aquatic areas include the Trout cod, Murray cod, Macquarie perch, and the Murray crayfish.
Overall, salmonids were the most prevalent group of fish detected in the area through eDNA, including Brown, Rainbow and Brook Trout; Talbingo reservoir is stocked with Rainbow Trout for recreational fishing. Other native fish species included Murray Cod, Golden Perch, several Galaxias species, Two-spined Blackfish, Australian Smelt, Short-finned Eel, and Flathead Gudgeon.
Invasive species were detected in both reservoirs, including the Goldfish, Eastern Gambusia and Carp. Additionally, there were Redfin Perch detected in the Talbingo reservoir, but none in the Tantangara.
Three spiny crayfish taxa were detected including Reik’s Crayfish, Murray Crayfish, the Common Yabby, and the Alpine Spiny Crayfish.
Impacts on aquatic ecology
Impacts to the aquatic ecology of the Main Works area and subsequently connected waterbodies are somewhat similar to those that were identified by the Biodiversity assessment, including habitat fragmentation, degradation, or destruction, pollution, and introduced species.
​
A change in groundwater in some areas, created by the equalisation of the Talbingo and Tantangara reservoirs, may create the fragmentation or destruction of some seasonal waterbodies, leaving some populations isolated and more vulnerable. In particular, the declining water levels can leave organisms stranded or isolated in unsaturated areas. For example, the survival of stygobiotic amphipods and syncarids in unsaturated sediments is limited beyond 48 hours; a decrease in water levels could severely impact stygofauna populations. The lowering of the water table may impact the survival of connected aquifers, swamps, or alpine bog systems, and subsequently their ecologies. However, the assessment stated that “if groundwater decline is slow or gradual in areas where predicted drawdown is greater than 20 m, it may present opportunities for stygofauna to migrate to saturated areas whilst drawdown is occurring, resulting in minimal impacts”.
Impacts to terrestrial ecosystems also impact aquatic systems. For example, clearing of habitat may create changes in run-off regimes and affect bank stability. This may impact water quality as sediment is washed into water bodies; potentially impacting pH, salinity, dissolved metals, and suspended sediment levels, and reducing dissolved oxygen levels. Accidental release of chemicals and fuels from construction, such as hydrocarbons, heavy metals, or sewage may impact ecological processes in waterways. The mixing of water between the Tantangara and Talbingo reservoirs will also create a new equilibrium, affecting the water parameters of both. However, the assessment states that the risk of negative impacts to aquatic ecology from changes to water quality or temperature in the reservoirs is considered to be low.
​
The noise of dredging will also be of concern. As dredging will take place within enclosed waters, the intensity and effects of underwater noise are likely to be intensified as sound reflects off hard surfaces. However, it is believed that the effects of dredging related sound are likely to be negligible and temporary, and include avoidance responses rather than physiological damage.
​
Transportation of water between the reservoirs could also result in the translocation of predatory fish species such as the Redfin Perch (Perca fluviatilis) and Eastern Gambusia (Gambusia holbrooki). These species eat aquatic invertebrates, other fish, and frog species; affecting food chains and introducing competition for native predatory species.
The increase of feral cat numbers could negatively impact native species populations
Biodiversity impacts mitigation
Many mitigation strategies were recommended to alleviate impacts on biodiversity.
This included the suggestion to abandon some unnecessary infrastructure plans to reduce the overall environmental impact of Snowy 2.0, such as the Plateau power station complex and the southern communications route.
Additionally, some mitigation strategies proposed alternative sites for some infrastructure; using existing firetrails and lower-quality or previously cleared locations, rather than clearing or disturbing areas that surveys had identified as key habitat for threatened species. This was recommended for the Marica power station complex, the Marica ventilation shaft, and the southern communications route at Boggy Plain, to areas that had been historically cleared to reduce impacts on sensitive grasslands and alpine bog habitat.
The final main mitigation strategy was to develop a 50m buffer zone along the Yarrangobilliy River to protect key habitat identified for threatened species during surveys.
Critique
Overall, the assessments seemed extensive and thorough. For example, for the assessment of fauna, species-specific mitigation strategies were considered for each threatened species present or near the Main Works site. As each species will react differently to each impact caused by the development of Snowy 2.0, this is a crucial and well-executed part of the Biodiversity assessment.
​
It was also positive to see that survey techniques for both Biodiversity and Aquatic Ecology assessments were conducted independently to reduce bias, by experts in relevant fields of botany, aquatic biology, ecology, and zoology. Contracted organisations to conduct surveys and research included the University of Sydney, EnviroDNA, Charles Sturt University, and the Arthur Rylah Institute for Environmental Research, among others. However, there is some scepticism that bias has been completely removed in this report, due to the fact that Snowy Hydro Limited funded all research.
Additionally, given the scope and scale of this project, the fact that many impacts were considered minimal is surprising and potentially suspicious. At times, the reports felt somewhat rushed and curated to present Snowy 2.0 as completely non-invasive.
​
Initially, there was scepticism regarding one of the methods used to record the presence of frogs within the area. Supposedly, researchers walked along transects on the edges of riparian areas, shouting “Hey frog!” and recording any call responses.
​
Aquatic ecology impacts mitigation
Many of these impacts were deemed to be low in probability, and thus have no mitigation strategies in place, except for the potential of the introduction of invasive species.
For example, the Redfin perch is only found in the Talbingo reservoir. However, once the two reservoirs are connected, without preventative measures it is highly likely that larvae or egg masses will survive being pumped between Talbingo and Tantangara and colonise the Tantangara reservoir. From there, it is also certain that they will further colonise the Eucumbene river, The introduction of another large predatory fish species would be a potentially devastating impact to local waterbodies.
As such, mitigation measures include deterrence and controls to prevent movement into the pumping areas, through electric barriers, acoustic systems, bubble curtains, light controls, pheromones, screens, and UV treatments.
Bubble curtains may be used to deter fish from moving into certain areas.
This method sounded like an oversight in the editing process. However, personal communications with herpetologists that have worked with frogs in the Snowy Mountains before confirmed that this method was in fact legitimate.
​
Finally, there were some issues with the assumptions in some of the research methods. For example, in the faunal surveys, it was assumed that because terrestrial species were not observed, they were simply not present at the site. It may have instead been that species were in fact present at the site, but the species may have just been incredibly cryptic, or surveys were conducted at the wrong season for them to be visible. For example, the Northern Corroboree frog was not considered to be present within the Main Works area, but individuals of these species are tiny and hide in moss, and usually only call at certain points of the year. These critically endangered frogs may have indeed been present at the site, but were just potentially not observed.