Actual or likely harm: s 241(1)(a) of the POEO Act
48An assessment of harm in the present case requires further consideration of the immediate environment of both Bora Creek and the Goulburn River. However, before turning to that consideration, it is important to notice the definition of the phrase "harm to the environment" as defined in the Dictionary to the POEO Act. That definition includes:
"any direct or indirect alteration of the environment that has the effect of degrading the environment and, without limiting the generality of the above, includes any act or emission that results in pollution."
It is also important to notice that harm is not mitigated by the fact that the waters into which pollutant is discharged are, at the time of discharge, already disturbed or modified (Environmental Protection Authority v Waste Recycling and Processing Corporation at [149]).
49I have already described Bora Creek as an ephemeral stream. In the section affected by the four discharges relevant to the charge and downstream to its confluence with the Goulburn River, the Creek is described as being more often dry than wet, with pools formed following rain present only for a short time after stormwater discharges. The Statement of Agreed Facts acknowledges that there is no established aquatic ecology in the lower sections of the Creek above the Goulburn River confluence. Macroinvertebrate fauna sampled in that section of the Creek after stormwater events are generally derived from overflows from the permanent inline farm dams constructed within the Creek catchment.
50Further, there are no native fish in Bora Creek as it is isolated from the Goulburn River by a high vertical waterfall discharge from the Creek to the riverbed. That waterfall is impassable to fish. At the point where Bora Creek discharges over this waterfall into the Goulburn River, the riverbed is described as supporting an almost total cover of water reeds (Cumbungi and Phragmites) that are established on deep sediment beds. This water reed ecosystem acts as a major nutrient and sediment filter to the Goulburn River catchments. These catchments are acknowledged contributors of sediments, turbidity and nutrients to the River.
51The volume of sediment-laden water entering the Bora Creek and Goulburn River systems from Discharges 1, 2 and 3 is not known. The evidence records observations of Discharges 1 and 2 to which I have already referred. The first of these involved discharge observed for two hours while the second involved discharge for about one and a half hours. The period during which any discharge was occurring prior to the observations being made is not known.
52Discharge 4 resulted in an estimated volume of 16,200 litres of dirty water flowing into Bora Creek. This discharge is said to have occurred over a period of about 90 minutes. While the total volume of sediment-laden water discharged between 8 June and 23 June from the Infrastructure Area cannot be calculated, it may be deduced from the observations made that it was not insignificant.
53The evidence indicates and the defendant accepts that the commission of the offence resulted in the visible pollution of Bora Creek and a stretch of the Goulburn River for a distance of something less than six kilometres. Mr Miller described the water in Bora Creek from Discharge 1 as "yellow" in colour. Officers of the prosecutor described the water in Bora Creek and the Goulburn River at its confluence with the Creek as "the colour of milky coffee".
54On 9 June Ms Imrie observed sediment-laden water in the Goulburn River five kilometres downstream of its junction with Bora Creek. When observation of the River was made by officers of the prosecutor on 10 June at a location approximately two kilometres downstream of the Bora Creek confluence, they described the waters in the River as being "discoloured and turbid" but not as discoloured as the water observed in the River at its confluence with the Creek.
55In addition to the visual impact, the water sample data to which I have earlier referred indicates that the quality of water discharged both to Bora Creek and the Goulburn River was carrying significantly elevated concentrations of total suspended solids, significantly elevated levels of turbidity and significantly elevated concentrations of nutrients such as nitrogen and phosphorous. These elevated levels had potential to impede healthy aquatic productivity and harm the health of the habitat of aquatic organisms, particularly bottom dwelling organisms such as snails and bivalves. They also had the potential to impact upon minute invertebrates and algae that use the surface of aquatic plants or other substrates as habitats.
56The prosecutor submits that actual harm occasioned by the four discharges was minimal. It also submits that there were no long term effects from each of the discharges or from their cumulative effect.
57Apart from the visual effect of the discharges and the elevated levels of suspended solids, turbidity and nutrients, it is correct to observe, as the defendant submitted, that there is no evidence of other actual harm. Clearly, there was potential for harm. That potential arose from the degraded quality of the water that was discharged. The potential effect upon aquatic ecosystems and biota cannot be ignored. Increased concentration of nutrients such as nitrogen and phosphorous in Bora Creek and the Goulburn River resulting from the offence had the potential to stress the aquatic environments of those waterways. One of the consequences of that increased nutrient load was potential for excessive growth of nuisance aquatic plants and the development of algal blooms.
58The four discharges that are the subject of evidence gave rise to the potential for serious environmental harm. However, taking into account the matters to which I have referred, including the submission of the prosecutor, I consider that the environmental harm, particularly in the long term, was towards the lower end of the range.