Inland waters
Queensland's rivers and aquifers are under pressure from increasing levels of water diversion for consumptive purposes. The main factors affecting water quality are eutrophication, chemical contamination and salinity; these are largely the result of discharges from urban and agricultural areas. Other key factors affecting river health are the condition and extent of riverine vegetation, disruption of stream flow, and invasive species. Wetland management is becoming a more important issue. In particular:
- Long periods of below-average rainfall and high levels of consumption have led to a widespread decline in groundwater levels. Groundwater in more than half the state's groundwater management units is either overabstracted or approaching the upper limits of sustainable abstraction.
- Uncontrolled bores and excessive water extraction have caused widespread falls in pressure levels in the Great Artesian Basin. Many natural springs no longer flow.
- In July 2002, Queensland had 567 open artesian bores and 15 305 km of bore drains. Approximately 95% of the water flowing is wasted and facilitates the spread of pest plants and animals.
- Bore rehabilitation began in 1989. Between 1989 and 1999, 347 bores were rehabilitated and 2078 km of bore drains replaced with piping. Between 1999 and 2002, a further 69 bores were rehabilitated and 1747 km of bore drains replaced. These works save approximately 80 000 ML of water each year.
- Groundwater quality ranges from poor to moderate. Elevated nitrate levels and salinity are the main problems caused by human activities.
- Surface water consumption reached 2 969 000 ML in 1996-97, a 145% increase since 1983-84. Most of that water was used for irrigation (73%) and urban and industrial uses (26%).
- There were 25 875 water licences in 1998, 26 428 in 2001, and 22 478 in 2002.
- Since 1999, approval has been given for the construction of two new dams and two new weirs, and for the raising of another dam and another weir.
- The Haughton, Kolan, Macintyre, Moonie, Condamine and Warrego rivers are categorised as highly regulated, and the Condamine and Kolan rivers are also subjected to high water abstraction.
- The Water Act 2000 introduced water resource planning, and the Queensland Government has undertaken a range of rural water use efficiency initiatives with agricultural industries.
- The main point sources of aquatic nutrients are sewage treatment plants and intensive animal industries, while eroded soil, plant litter, livestock manure and fertilisers are the main non-point sources. Most rivers have high phosphorus loads, while the Fitzroy and Burdekin also have high nitrogen loads.
- Cyanobacteria (blue-green algae) have been found in 70% of Queensland reservoirs, at least on a seasonal basis.
- Pesticide testing in the Condamine River between 1993 and 2001 found reductions in the levels of endosulfan measured (zero levels for 1999-2001). Atrazine and metolachlor were found in 72% and 65% respectively of samples tested, often at levels in excess of drinking water guidelines.
- Samples taken at a large proportion of monitoring sites in the Burnett-Mary, Fitzroy, South West, South East, Mackay-Whitsunday, Burdekin Dry Tropics and Southern Gulf regions exceeded guideline levels for salinity.
- South-east Queensland had the highest proportion of waterways with macro-invertebrate populations well below reference levels.
- Riparian vegetation along more than half of the stream lengths surveyed was in poor condition.
- There are widespread problems with riparian weeds throughout Queensland; the Fitzroy and central Burdekin river basins have the highest number and density of exotic weeds.
- Of Queensland's 71 000 km² of wetlands, 69% are seasonally or intermittently inundated, while 14% are tidal wetlands.
- The extent of wetland loss is unknown.
- The numerous barriers to the movement of freshwater fish have significant impacts on fish populations.
- Sixteen species of exotic fish have formed significant self-maintaining populations in Queensland waters. Carp, tilapia and gambusia are considered to pose the greatest risk. Most river systems (with the exception of the Lake Eyre and Gulf drainages) have been invaded by one or more exotic species.
- Commercial eel catches are declining, apparently due to overfishing and lack of recruitment.
- Six species of freshwater fish are considered critically endangered, and a further six are considered vulnerable.
Last updated: 19 May 2004