National Land and Water Resources Audit
State of the Environment Reporting
Water Quality Exceedence, Trend and Status Assessment for Queensland
Department of Natural Resources, Queensland
June 2000
Click here to download the complete report in PDF format (91 KB)
Please Note: PDF files are in Adobe Acrobat Version 4.0 format. You will need a copy of an Acrobat Reader in order to view them. Blind and visually impaired users can view the document using a tool available on-line from Adobe Systems that converts the PDF files on the fly to HTML.
Summary
The analysis of water quality conditions in Queensland is based on data held by Queensland’s Department of Natural Resources (DNR) and the Environmental Protection Agency (EPA). The DNR surface water database consists of about 34,000 sets of data collected from 1462 sites in rivers, streams and dams in Queensland. Most of these sites are located in the North East Drainage Division although some water quality monitoring has taken place in the other divisions. The EPA collects data from over 500 sites, of which 100 are classed as freshwater sites. The EPA sites used for this study were flagged as freshwater sites however subsequent analysis of these has cast some doubts on this, as it appears that several of these sites may be under some estuarine influence.
For all of the waterways, the management objectives on which the exceedence analyses were derived were based upon the ANZECC (1992) and NHMRC (1996) water quality guidelines. In assessing the quality of surface water for agricultural use, the guidelines developed by Gill (1986) were used. The terms good, fair and poor were used to rate the exceedence values of the various water quality parameters for aquatic ecosystem protection, drinking water and agricultural use.
Generally, Queensland does not suffer the major salinity problems experienced in other states. However, this assessment has identified some areas within Queensland that have experienced or are experiencing changes to the salinity regimes of surface waters. For example, in Barambah Creek in the Burnett River basin, where extensive land-clearing has taken place for agriculture and grazing, very high levels of conductivity were noted. Furthermore, in some parts of the Condamine-Balonne and Burdekin basins, levels of surface water salinity are increasing. From this assessment, it is clearly important that ongoing monitoring of salt levels is maintained by government organisations and through community programs, such as Saltwatch and Waterwatch.
Turbidity levels in Queensland’s surface waters vary substantially, as would be expected from the diverse local environments and types of development. However, throughout the vast majority of Queensland’s monitored waterways, surface water turbidity levels were found to be high and unsuitable for drinking water, indicating that Queensland’s water would normally require substantial treatment before use.
The most turbid conditions were detected in the inland basins (the Fitzroy, Condamine-Balonne and Burdekin), where turbidity levels frequently exceed ANZECC (1992) guidelines for the protection of aquatic ecosystems. These conditions have been partially attributed to the widespread removal of native vegetation for various activities, such as cropping, grazing and mining. However, there is evidence from this assessment and from previous studies that the inland basins’ natural soil conditions, topography and climate may also have a significant input into the surface waters’ high turbidity levels (McNeil et al 2000). As recommended by ANZECC (2000), local guidelines need to be developed to determine whether the poor turbidity levels in these basins are primarily due to natural processes or whether the water quality would improve in response to initiatives in land management.
Monitoring of Total Phosphorus (TP) and, in particular, Total Nitrogen (TN) concentrations has been very limited in some areas of Queensland, and, as such, it is not possible to make a firm general assessment of the state of Queensland’s waterways in relation to nutrient levels. From the limited dataset, it was found that TN and TP concentrations are very high in the more populated catchments of Queensland, such as the Brisbane and Logan-Albert River basins. It has been postulated by Moss et al (1996) that this may be primarily attributed to point source loads, mainly from treated sewage discharges, and urban stormwater runoff. TN and TP concentrations are also elevated in the coastal plains of several central coast basins, such as the Fitzroy, Mary, Proserpine, Ross and Plane River Basins, and in the Murray-Darling. At some sites, this is possibly attributable to point discharges (treated sewerage and waste effluent from animal husbandries), but at others it may be primarily related to land use factors, such as the removal of native vegetation for development, and the application of fertiliser to agricultural land. Given that many of Queensland’s central coast and inland basins are subject to similar types of catchment development, it is possible that TN and/or TP concentrations are elevated in a significant proportion of Queensland’s waterways. It would be thus worthwhile to undertake routine monitoring of nutrient levels in order to determine the extent of nutrient loading into the major rivers and storages of Queensland.
As would be expected from the diverse local environments and types of development, pH levels vary throughout Queensland’s basins. In the relatively undeveloped Wet Tropics of the North East Coast Drainage Division, surface waters are generally acidic, which, according to the ANZECC (1992) and NHMRC (1996) guidelines, renders the water unsuitable for aquatic ecosystem protection and for the supply of drinking water. Previous studies, however, have indicated that these conditions may be natural - the waterways’ low conductivity levels, sandy/rocky substrates and high concentrations of sodium chloride, result in a bicarbonate poor environment, thereby promoting acidic conditions (McNeil and Cox, in press). Furthermore, due to the catchments’ densely vegetated ranges, organic matter input into the river systems would be very high, which is also likely to have some input into the surface water’s low pH levels.
Low surface water pH values were also detected in the coastal plains of some South-East (Logan-Albert and South-Coast) and Central coast basins of the State. With respect to some of the central coast basins, the acidic conditions may be partly attributed to local organic acid input from the sugarcane areas. Reasons for the low pH values in the Logan-Albert and South-Coast basins are not clear but may be related to organic matter input from stormwater and terrestrial runoff, and treated effluent discharge.
With the exception of two sites located in Oxley Creek in the Brisbane River basin, faecal coliform concentrations have not been routinely monitored in Queensland’s waterways. To adequately understand the conditions of waterways in Queensland for recreational use and human use, faecal coliform concentrations may need to be monitored more extensively.
To date, water quality monitoring of Queensland’s rivers has been largely confined to the South East and Central regions of the North East Drainage Division. Consequently, little is known of the water quality in the western and northern areas of the State. The absence of any significant data for waters in these areas is largely due to logistic difficulties and high costs involved in undertaking any form of routine monitoring in the area as well as a historical lack of perceived water quality issues. In the past, there has been relatively little development of these regions for either agriculture or human settlement and as a result, water quality monitoring was not considered essential. However, some of these regions, such as the Murray-Darling, have been identified as having significant water quality issues, particularly in regards to salinity and nutrient concentrations.
With respect to regions that are relatively undeveloped, such as in Cape York, the current, near pristine nature of the area presents a rare opportunity to collect good baseline data. Such data would be invaluable for assessing the impacts of any future development, both locally and as a comparison to areas further south.
Click here to download the complete report in PDF format (91 KB)
Please Note: PDF files are in Adobe Acrobat Version 4.0 format. You will need a copy of an Acrobat Reader in order to view them. Blind and visually impaired users can view the document using a tool available on-line from Adobe Systems that converts the PDF files on the fly to HTML.
 |
|
|
|||||||||||
