There are two main sources of surface water quality data for the Galilee subregion. This includes the Surface Water Ambient Network (SWAN) monitoring programme operated by the Queensland Government (Department of Environment and Resources Management, 2011) and information collected under the Lake Eyre Basin Rivers Assessment (LEBRA) programme (Cockayne et al., 2013; Sternberg et al., 2014). The SWAN monitoring programme has been in operation since 1990 and it monitors water quality parameters at selected stream gauge sites using auto-sensor recorders. The LEBRA programme commenced in 2011 and collects water quality data using data loggers and some in situ sampling. While other water quality data are available, the water quality indicators assessed in this report are electrical conductivity (EC) and turbidity. Data are based on SWAN’s 2004 to 2008 and LEBRA’s 2011 to 2013 data.
EC is a measure of salinity that is often determined in the field using a conductivity sensor. The EC values are then converted to total dissolved solids (TDS) using an appropriate conversion factor. The conversion factor depends on the chemical composition of the TDS and can vary between 0.54 and 0.96. A value of 0.67 is commonly used as an approximation if the actual factor is not known.
Current status of water quality in the Galilee subregion has been assessed against the Queensland Water Quality Guidelines (QWQGs) of the Department of Environment and Heritage Protection (DEHP). The QWQGs were derived based on the Australian and New Zealand Environment and Conservation Council (ANZECC) guideline values or descriptive statements for environmental values to protect aquatic ecosystems and human uses of waters (ANZECC/ARMCANZ, 2000). The QWQGs are intended to address the need identified in the ANZECC Guidelines by providing guideline values that are specific to Queensland (Department of Environment and Heritage Protection, 2009).
1.5.2.1.1 Water quality in the Cooper creek basin
The availability of water quality data for the Cooper creek basin is extremely poor compared to other river basins in Australia. There are three water quality monitoring sites (i.e. Bowen Downs, Longreach and Blackall) in the Galilee subregion that occur in the Cooper creek basin. Among the sites, continuous auto-sensor records of EC are available for Longreach station (since 1993). In addition there are three data logger sites in the Galilee subregion operated by the LEBRA programme since 2011. The LEBRA programme also collects occasional in situ measurements every year in its 50 sites within the Lake Eyre Basin, of which 20 are in Queensland.
The EC values in this basin are generally lower than the water quality objective trigger value. The 75th percentile baseflow trigger value for EC is 205 μS/cm for the Lake Eyre region (Department of Environment and Heritage Protection, 2009). A typical example of auto-sensor data at Longreach gauging site is shown in Figure 10 for 2005 to 2013. Gaps in the measured EC auto-sensor dataset represent periods where data were not collected due to either periods of no flow or monitoring equipment failure. EC varies between 44 to 258 µS/cm with a mean of 155 µS/cm. The median EC for baseflow is about 200 µS/cm and for high flow it is 100 µS/cm with an overall median of 157 µS/cm, however occasional high EC values occur anomalously at mid-flow ranges, particularly between 0.1 and 10 m3/s (Department of Environment and Resources Management, 2011). These may be the result of the ‘first flush’ of a flow event after a dry period, where accumulated salts are cleared from the intermittently flowing watercourse. In general EC levels are low and stable at each of the gauging stations but subject to occasional high pulses at some sites. Data from the LEBRA logger sites also showed a general pattern of increasing EC throughout the low or no flow periods, followed by sharp lowering during high-flow events. At some sites there is a distinct initial rise in EC when the first flood water arrives (Cockayne et al., 2013).
Turbidity in this basin is generally high and subject to varying trends across the basin as a result of local influences. It appears to reverse from a declining trend in the north of Cooper Creek, to an increasing trend before crossing the Queensland–South Australia border (Department of Environment and Resources Management, 2011). Due to the tendency towards forming isolated waterholes during the extended dry seasons in this basin, differing turbidity trends may be more representative of local influences than generally deteriorating water quality further downstream (Department of Environment and Resources Management, 2011). In situ measurements at 17 sites (during spring 2011 and autumn 2012) show the turbidity varies from 4 to 354 NTU (Nephelometric Turbidity Unit), with a mean of 124 NTU across the Cooper creek basin (Cockayne et al., 2013).
The dashed line (---) shows the water quality objective trigger value.
Data: Queensland Department of Natural Resources and Mines (Dataset 1)
1.5.2.1.2 Water quality in the Flinders river basin
The availability of water quality data for the Flinders river basin is very limited. In the northern part of the Galilee subregion, there is only one water quality monitoring site at Richmond. Continuous auto-sensor data have been available for this site since 2000. In addition some sampled data are also available for Richmond under the SWAN programme.
At Richmond, EC is quite variable at 150 μS/cm during high flows, commonly ranging up to 450 μS/cm as flow declines during dry conditions. Under the Queensland Water Quality Guidelines (QWQGs) the 75th percentile baseflow trigger value for EC is 435 μS/cm for the Gulf region (Department of Environment and Heritage Protection, 2009). Exceptionally high EC values exceeding 3000 μS/cm occasionally occur at flows of between 0.01 and 0.1 m3/s (Department of Environment and Resources Management, 2011). A typical example of auto-sensor data at Richmond gauging site is shown in Figure 11 for 2005 to 2013. A long data gap can be seen between years. This represents periods where data were not collected primarily due to no flow conditions but sometimes due to monitoring equipment failure. The value of EC varies between 11 to 993 µS/cm with a mean of 397 µS/cm. The median EC for baseflow and high flow are 475 µS/cm and 210 µS/cm respectively, with an overall median of 366 µS/cm. EC values are generally higher for this basin compared to Cooper creek basin.
The dashed line (---) shows the water quality objective trigger value.
Data: Queensland Department of Natural Resources and Mines (Dataset 1)
From the limited available data a conclusion cannot be drawn on overall water quality. However, where data are available, water quality appears to be in good condition; that is below the water quality objective trigger value. Also, spatial variabilities in the magnitude and ranges of both EC and turbidity were noticed. Although there are some broad regional trends in EC, turbidity appears to be dominated by local influences. There is much uncertainty in condition and trend assessments (Department of Environment and Resources Management, 2011).
1.5.2.1.3 Water quality in the Burdekin river basin
In the Burdekin river basin, there is only one water quality monitoring station, situated at Violet Grove on Native Companion Creek. This is in the eastern part of the Galilee subregion, where most potential coal mining sites are located. It has maintained data records since 1999.
A typical example of gauge data at Violet Grove on Native Companion Creek is shown in Figure 12 for 2000 to 2013. The gap between data represents periods where data were not collected primarily due to no flow conditions. EC varies between 16 to 753 µS/cm with a mean of 285 µS/cm. The median EC for baseflow is about 273 µS/cm and for high flow it is 151 µS/cm with an overall median of 245 µS/cm. EC values are generally higher for this basin compared to Cooper creek basin but less than Flinders river basin.
The dashed line (---) shows the water quality objective trigger value.
Data: Queensland Department of Natural Resources and Mines (Dataset 1)
The temporal trends observed in the EC of river sites are likely linked to the local climate and flow regime. The lower EC levels were present at the end of the wet season during which time the heavy rainfall would have caused dilution of the salts present in the river. The observed increase in EC as the dry season progressed is likely related to the cumulative effects of the evapo-concentration of the salts and groundwater inputs.
As a part of the Alpha Coal Project, water quality parameters in the upper Belyando river catchment were investigated by Hancock Prospecting Pty Ltd based on available EC and turbidity data from 1978 to 2010. The 20th and 80th percentile values for the gauging site are 105 and 213 µS/cm respectively (Hancock Prospecting, 2010). Under the QWQGs the 75th percentile baseflow trigger value for EC is 170 μS/cm for the Belyando river catchment (Department of Environment and Heritage Protection, 2009).
Turbidity was found to be generally stable across the catchment (Department of Environment and Resources Management, 2011) but it is relatively high compared to Cooper creek basin. The median, 20th percentile and 80th percentiles turbidity values are 200, 57 and 452 NTU respectively (Hancock Prospecting, 2010).
1.5.2.1.4 Gaps
Water quality data for the surface water systems in the Galilee subregion is very limited in terms of data points and number of data. It is therefore difficult to draw a conclusion on overall quality based on available data.