Issue: Catchment quality
How has catchment quality changed?
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A grazing property near Braidwood
Insufficient data were available to adequately assess changes to, or impacts on, many aspects of catchment quality within Palerang Council Area during the reporting period. As a result, changes in erosion, salinity, ground and surface water quality, condition of terrestrial and riparian ecosystems and impacts of these changes could not be reported.
Drought was potentially the most significant event impacting on catchment quality within the council area during the reporting period. At least 95% of the council area was drought-affected during late 2002 to mid 2004. The drought continued beyond the end of the reporting period.
Potential effects of drought included:
- in all catchments—increased erosion, reduced vegetation vigour and increased pressure on native vegetation, increased environmental stress on waterways
- in all catchments—a shift from cropping and mixed farming to grazing
- in the catchments with greater cover of native forest (Moruya, Shoalhaven and Murrumbidgee catchments)—increased fire risk but more resilience to drought-induced land degradation
- in all catchments—decreased availability of surface and ground water resources (see the Resource use issue)
- in all catchments—small increases in some areas of St Johns Wort, Serrated Tussock and Blackberry
- in most catchments—increases in the range of dingoes and wild dogs and feral pigs may have been partially due to drought conditions and the dispersal of these animals in search of food.
Again, impacts were not known at the end of the reporting period.
Where are the 'hot spots'?
Treated effluent from sewage treatment plants is discharged to Turallo Creek (Lake George catchment), Molonglo River (Murrumbidgee River catchment) and Flood Creek (Shoalhaven River catchment). One accidental discharge of sewage occurred from the Braidwood Sewage Treatment Plant to Flood Creek during the reporting period. No information regarding the impacts of this on catchment quality was available.
Scattered areas of extreme gully erosion occurred throughout all catchments within the council area. However the densest areas of extreme gully erosion occurred in the Lake George catchment and in the Majors Creek area of the Moruya River catchment.
The largest areas of severe to extreme sheet erosion occurred within the Lake George catchment, near Captains Flat in the Murrumbidgee River catchment and along the lower Shoalhaven River in the Shoalhaven River catchment. Minor areas are also scattered throughout these catchments.
The most extensive areas of dryland salinity outbreaks occurred within the Yass River subcatchment of the Murrumbidgee River. Other areas occurred within the Lake George catchment and the Mongarlowe River and Boro Creek subcatchments of the Shoalhaven River.
A small area of agricultural land was converted to timber production forests within the Murrumbidgee River, Shoalhaven River and Lake George catchments within the council area during the reporting period. Potential impacts of timber production may include increased erosion and siltation.
Eight out of ten streams surveyed in the Shoalhaven River catchment within the council area had high proportions of native riparian vegetation removed and nine had gully or streambank erosion issues. These streams included the Shoalhaven and Mongarlowe Rivers and Back, Round Mountain, Jerrabattgulla, Boro and Reedy Creeks. In addition, the majority of Jerrabomberra Creek in the Murrumbidgee River catchment was reported to have a degraded and impoverished riparian zone.
Dingoes and wild dogs and feral goats occur within the Murrumbidgee, Shoalhaven and Moruya River catchments. The main populations of these species were within the Moruya River catchment. Distribution of dingoes and wild dogs and number of feral goats increased during the reporting period.
Wild deer occurred throughout the Murrumbidgee, Shoalhaven and Lake George catchments, with the main population being within the Lake George catchment. This species increased in numbers during the reporting period.
Feral pigs occurred within all catchments in the council area, with the main populations being along the Shoalhaven River corridor. This species underwent a slight reduction in numbers but increased in distribution during the reporting period.
The main populations of Scotch Broom occurred within the Captains Flat area in the Murrumbidgee River catchment and the Majors Creek area of the Moruya River catchment. There was a reduction in areas of infestation of this species during the reporting period.
Other factors relating to catchment quality
Guidelines for assessing water quality changed from last reporting period. Two water quality monitoring sites were within the Murrumbidgee and the other was in the Shoalhaven River Catchment. The general quality of surface water at one of the Murrumbidgee sites was classed as poor due to high salt and low dissolved levels. Overall water quality at the other two sites was classed as good although exceedences did occur from time to time. None of these sites were reported in the previous reporting period.
Parts of the Murrumbidgee River and Lake George catchments had a more reduced vegetation vigour than the remainder of the council area during the months of October to November 2002. In addition, these catchments, together with the Braidwood area within the Shoalhaven River catchment, had a more reduced vegetation vigour during the months November to January 2004 in drought years than did the remainder of the council area.
Conservation reserves occur within all catchments in the council area. During the reporting period, sixteen new reserves and additions to three existing reserves were dedicated. These lands were predominantly timber production forests. This would have potentially have had a positive effect on catchment quality by decreasing erosion and runoff due to rehabilitation of logging tracks and reduced vegetation disturbance.
A number of small wildfires occurred within the council area during the reporting period, most of which were within the Shoalhaven and Moruya River catchments. It is unknown what impacts they had on catchment quality.
Strongly acidic soils occur throughout the majority of the council area in all catchments. Areas not within this class include agricultural lands along the Shoalhaven River, Araluen Creek (Moruya River catchment) and within the subcatchments of Taylors and Butmaroo Creeks (Lake George catchment). Although the lands along the Shoalhaven River and Araluen Creek were not in this class, they had a high to critical risk of soil acidification. Impacts of acid soils may include decreased crop yields, poor performance of perennial pastures, and increased erosion, siltation and salinity.
Foxes and rabbits occurred across all catchments within the council area. Rabbits decreased during the reporting period while fox populations remained stable.
Four of the five priority weed species occurred throughout the council area potentially in all catchments. Overall densities of all species decreased during the reporting period.
What has been done to address catchment quality?
At least 13 projects were undertaken by community groups and council to improve catchment quality within the Shoalhaven River catchment. Activities undertaken included revegetation; erosion and siltation control; riparian management, surveys of riparian condition, and management incentives; biodiversity restoration on degraded landscapes; and salinity remediation.
At least a further eight projects were undertaken within the Murrumbidgee River catchment and included activities such as revegetation, erosion control, weed control, linking vegetation remnants and riparian management.
In addition, at least two projects were undertaken within Lake George catchment and another three in the Moruya River catchment. The Lake George projects involved revegetation measures, while the Moruya projects included erosion and weed control and riparian management activities.
Activities undertaken by council during the reporting period to address catchment quality include:
- control of five priority pest plant species resulting in reductions in overall densities for all species
- the introduction of water restrictions in Bungendore township in the Lake George catchment during 2002–04.
The Bidgee Banks and Beyond Bidgee Banks projects undertaken by Greening Australia and Department of Natural Resources included actions for riparian restoration, revegetation and erosion control.
Large areas of timber production forest were converted to form 17 new conservation reserves across all catchments and provide additions to three existing conservation reserves in the Shoalhaven, Murrumbidgee and Moruya River catchments.
Other actions to conserve biodiversity would have contributed to catchment quality within the council area (see the Conserving biodiversity issue).
The future—what does this mean for Council?
Continued lack of data about many aspects of catchment quality within the council area will mean only partial assessment of it is possible, and with it, a corresponding risk of council activities having inadvertent adverse impacts.
Lack of ongoing monitoring of erosion, sedimentation, salinity and ground and surface water quality within the council area may hamper conservation efforts, as impacts from urban and rural development and other pressures (e.g. fire, drought, landuse) cannot be determined and remediation measures cannot be planned. Monitoring is also essential to determine whether environmental plans and strategies and on-ground management projects are achieving the desired catchment management outcomes.
Because of lack of resources in the short term as a result of amalgamation, council may need to actively pursue partnership programs with State Government stakeholders and formulate other innovative methods for funding its environmental management program.
Council needs to maintain appropriate effort and resources in the following areas of its environmental management.
- Ensure impacts on catchment quality are considered in landuse zoning, assessment of development applications, road management, water supply works, waste water management and solid waste management. These activities need to include consideration of land capabilities and potential impacts on ground and surface water quality.
- Help ensure appropriate monitoring programs are in place to measure the effectiveness of council's environmental policies, strategies, management activities and on-ground restoration projects in achieving desired land and water management outcomes.
- Support and encourage community involvement in sustainable land and water management and monitoring.
- Maintain close liaison with NSW State Government agencies to encourage programs of data collection. especially for monitoring soil loss and erosion, salinity, sustainable land and water management systems and to help ensure Council has up-to-date knowledge about the condition of the council area's catchments and associated management issues relevant to them.
- Work closely with the Southern Rivers and Murrumbidgee Catchment Management Authorities and the Sydney Catchment Authority to help ensure consistency in approach to catchment-scale land and water management and complementary actions to achieve this.