Ecological and geochemical impact of an underground colliery waste discharge to a river

This study investigated the impact of mine wastewater disposal to a nearby river (the Bargo River). Mean electrical conductivity (EC) increased in surface waters below the mine discharge, rising more than six times from (219.5 μS/cm) upstream to 1551 μS/cm below the waste inflow. River pH increased from 7.12 (upstream) to 8.67 (downstream). The mine discharge strongly modified the ionic composition of the river. The mean concentration of several metals in the river were increased due to the mine wastewater. Nickel increased from 1.0 μg/L (upstream) to 32 μg/L (downstream). Zinc increased from 3.5 μg/L (upstream) to 23.5 μg/L (downstream). Our study also assessed the biological uptake of pollutants by growing weeping willow (Salix babylonica) cuttings in mine wastewater and contrasting to ‘control’ cuttings grown in river water from upstream of the mine. After growing in the laboratory for several weeks, the cuttings accumulated metals, dominated by barium, strontium and lithium. Results from the study constituted one of the most detailed geochemical and ecological studies investigating the impact of the coal mine waste discharge to an Australian river. Recommendations are suggested for improved regulation of the mine discharge to reduce its wastewater environmental impact

Elevated sodium concentrations in Australian drinking water supplies

Salt in the drinking water of many Australian water supplies could be adversely contributing to the ill-health of many people. Health care professionals often recommend low-sodium diets for patients with kidney disease, heart disease and cardiovascular disease. It is recommended that people on a low-sodium diet drink water with less than 20 mg/L of sodium. The sodium concentration of water supplies in many regional and remote regions of Australia often had water with elevated sodium (more than 20 mg/L) in their water supplies. In NSW 17 of the 21 regional water supplies tested had higher than 20 mg/L sodium. The issue of elevated sodium in many Australian drinking water supplies needs to be recognised more prominently. Sodium needs to be sampled more frequently and the results shared openly with consumers and health professionals. All water authorities that provide drinking water with sodium concentrations higher than 20 mg/L should be advising their customers of this fact as a high priority. People on low-sodium diets that have >20 mg/L sodium in their water supply should consider options to obtain low-sodium water

The use of citizen scientists to confirm the presence of platypus (Ornithorhynchus anatinus) in north-west Sydney

The platypus is an elusive species. Traditionally they have been hunted for their fur and now face several threats including drought, pollution and like many of our Australian icons, habitat loss from urbanisation. Sydney is undergoing rapid urbanisation. The population of platypus in Sydney is not well studied, is not well documented and poorly acknowledged. The aim of this project was not only to confirm the presence of platypus in the Cattai and Little Cattai Creek catchments in north-west Sydney but to get the community excited and engaged with waterway health using the platypus as an umbrella species. Working with a local volunteer community environment group, Cattai Hills Environment Network, a media campaign was conducted for the wider community to identify possible ‘hotspots’ which resulted in the mapping of 18 sample sites. Community members were recruited as citizen scientists to conduct simple environmental DNA (eDNA) sampling over a weekend in June 2020. Samples at eight out of the 18 sites contained platypus DNA which confirmed the presence of platypus in the north-west of Sydney. Using citizen scientists, lay members of the community, to be a part of this project, to take ownership in collecting data and contributing to the project allowed the community to connect with the waterways. The more that the community connect with the waterways the more they will work and advocate to protect it. This project could be adapted more broadly, not only for platypus in Sydney, but as a template of a successful citizen scientists project

Subsidence fracturing of stream channel from longwall coal mining causing upwelling saline groundwater and metal-enriched contamination of surface waterway

This study investigated a small waterway that had been impacted by upwelling groundwater due to recent geological strata fracturing caused by subsidence activity from longwall coal mining. Documents from the coal mine report that subsidence has undermined and fractured the stream channel for more than 10 years prior to this study. Mine documents also report many years of variably degraded water quality (salinity, elevated metals) in the reaches affected by fracturing. In this study, water quality of the stream was monitored over an 11-month period with water flow dominated by ground water upwelling through fractures in the creek channel. The upwelling water caused extensive modifications to the creek’s surface water quality relative to unmined reference sites. The mean electrical conductivity increased by seven times from 230 μS/cm at reference sites to 1833 μS/cm below the upwelling. Dissolved oxygen in the upwelling groundwater was extremely low (2.7% saturation) and was mildly acidic (5.8 pH). Alterations to the ionic composition included sevenfold increases in magnesium, sodium, and chloride concentrations. Heavy metals iron and manganese increased by more than ten times, with nickel by more than 60 times compared to the reference sites. The alteration to ionic composition was inferred to be saline groundwater intrusion. The ecological impacts of such large modifications to surface stream water quality would be hazardous for integrity of downstream aquatic ecosystems

Underground coal mining and subsidence, channel fracturing and water pollution : a five-year investigation

Subsidence from underground coal mining can be a problematic issue. Our study investigated a waterway that had been disturbed by a coal longwall that made multiple passes directly under it. The most obvious impact was loss of stream flow through sections of fractured bedrock channel. Water quality of the stream was monitored over a 5-year period, where the creek had flow. Ochre-coloured water appeared in some sections of the creek. Salinity increased by four times from <250 (upstream) to 1195 μS/cm in subsidence affected zones. The concentration of metals such as zinc and nickel increased by many times to levels in exceedance of the ANZECC water quality guidelines for aquatic ecosystems. The macroinvertebrate composition of sections of the creek was strongly impaired and mosquitos were abundant. One sampling site was conducted where upwelling groundwater entered the creek through recent subsidence fractures, and below that point the creek flowed continuously during the most recent six months of the study. Mean electrical conductivity increased due to that upwelling, rising 6.8 times from (230 μS/cm) at upstream/reference sites to 1806 μS/cm below the upwelling. Dissolved oxygen of the upwelling groundwater was extremely low (2.7 %) and was also acidic (5.8 pH)

The effect of water quality, macroinvertebrate assemblages and habitat suitability on the distribution of Platypuses : a pilot study in Cattai Catchment, North West Sydney

The platypus (Ornithorhynchus anatinus) continues to persist in urban waterways with high pollutant concentrations, altered flow regimes, channel morphology, and degraded stream substrate and riparian zones. The purpose of this study was to determine whether water quality, specific habitat features, and macroinvertebrate assemblage influences the distribution of platypus as inferred by eDNA detection in a selection of 13 sites within the Cattai catchment, in North West Sydney. Sampling took place on two separate occasions: June 2020 and December 2020. Platypus eDNA was detected in 9 of the 18 sites and 5 of the 9 waterways surveyed. Platypus activity was strongly associated with the quality of their stream habitat (riparian vegetation, absence of sand and silt accumulation, and streams lacking dense growth of macrophytes). Platypus also appeared to avoid streams with ‘higher salinity', and lower dissolved oxygen. The effective conservation of this iconic species in peri-urban and urbanised catchments such as that of Sydney requires ongoing monitoring of population status and health, and prevention of further habitat damage by informed local population management strategies. This study indicates that the loss of riparian vegetation, an increase in aquatic weeds and increased sedimentation are important factors in developing local stream management improvements to sustain the population of platypus in the Sydney basin

Water quality and ecological recovery of a mountain stream after 60 years of receiving sewage effluent

In 1980 the sewerage system of the Blue Mountains (NSW) townships was inadequate. It had 12 overloaded sewage treatment plants (STPs) that provided incomplete treatment that caused widespread pollution of its streams. The last major STP discharge to be removed was Blackheath STP. It was permanently closed in June 2008. This study was conducted over 15 years. We used stream macroinvertebrates to measure the ecological changes that resulted following the STP closure. This began when it was still operating in 2003, then 16 months later (2009), and then in 2018, almost 10 years after its closure. This case study was a rare opportunity to study the recovery of a previously chronically impaired freshwater stream by decades of receiving poorly treated sewage wastes. We used a replicated quantitative ‘kick sampling’ technique and identified invertebrates to the family level to measure ecological health recovery of the small headwater stream. We found that the degree of ecological recovery was large but not complete, indicating a possible residual disturbance remaining. We suggest that one of the important factors that has enabled the recovery to date was the clean water quality and environmental condition of Hat Hill Creek upstream of the pollution

Challenges for management of treated sewage in NSW Southern Highlands rivers : drinking water catchment, World Heritage Area and platypus habitat

This study looked at the impact of four STPs located within the Southern Highlands to identify if environmental regulation was adequate in minimising pollution of waterways of high value. The Southern Highlands, Nattai and Wingecarribee Rivers are major tributaries to drinking water catchment, and Greater Blue Mountains World Heritage Area (Nattai River) as well as being platypus habitat. Results show elevated levels of nitrogen and phosphorus as well as heavy metals such as copper, zinc, iron and aluminium. The NSW EPA are responsible for enforcing discharge limits however, limits for heavy metals are not included in these licences and nitrogen and phosphorus limits significantly exceed ANZECC guidelines for environmental protection. Furthermore, a comparison of discharge limits between Southern Highland STPs and Western Sydney STPs revealed significant discrepancies as Western Sydney STP had tighter limits and included heavy metals despite not discharging into environments of high value. This study highlights the need for improved EPLs that reflect and state clear environmental goals for receiving water ways to ensure adequate environmental protection

14-month water quality investigation of coal mine discharge on two rivers in NSW, Australia : implications for environmental regulation

Ineffective environmental regulation of effluent discharged from an underground coal mine operation has enabled water pollution within two highly valued Australian rivers. This study investigated the impacts on water chemistry of the Bargo and Nepean rivers as a result of the continuous disposal of mine effluent from Tahmoor Colliery over a 14-month period. Coal mine effluent was saline (2180 μS/cm) and alkaline (8.7 pH), and strongly modified the ionic composition within both rivers. Ecologically hazardous concentrations of several metals were found in mine effluent, including aluminium (858 μg/L), arsenic (59.7 μg/L), nickel (60.7 μg/L), and zinc (49.4 μg/L). The effluent also contained elevated total nitrogen (2.89 mg/L) and the waste discharge contributed 67% of the median flow volume in the Bargo River below the discharge point. The plume of saline- and metal-enriched contamination extended at least 9 km downstream past the discharge point, impairing water quality in both the Bargo and Nepean rivers. This study reveals more than a decade of ineffective regulatory and governance systems that enable Tahmoor Colliery to continually release inadequately treated mine effluent

Community triggers EPA action on coal mine river pollution

In 2012 the upper Georges River was polluted due to coal mine wastewater inflows from the Westcliff Colliery. A local community group launched legal action against the mine. Evidence for the court case showed pollution involved elevated salinity and a suite of metals (zinc, nickel, copper and aluminium) at concentrations higher than recommended in the ANZECC guidelines. The pollution plume extended at least 22 km downstream. Macroinvertebrate samples confirmed that the river ecology was adversely affected by the coal mine wastes. The EPA license that authorised the waste discharge did not provide limits for any of the key pollutants (in 2012). Through the media the NSW Environment Minister intervened in the case and demanded action from the EPA to stop the pollution. In 2013 the EPA issued the mine with a revised license. It provided discharge limits for pollutants present in the wastes discharged from the mine, including salinity and numerous metals. Water samples collected in 2018 show that the water quality of the wastewater discharge has partially improved as a result of the new EPA license. However, low river flows have reduced dilution and increased the magnitude of the downstream plume for some pollutants in the Georges River