What the results tell us for Palerang
Most of Palerang Council Area is within low yield groundwater systems. Much of the area's groundwater was of drinking water quality, while the rest was generally suitable for some domestic, agricultural and limited industrial uses. Expert opinion suggests that groundwater levels in the council area would have dropped during the reporting period because of drought conditions.
The council area is within the upper Murrumbidgee, Lake George, Shoalhaven and Moruya river basins. Water management planning in the Murrumbidgee catchment, i.e. in the western half of the council area, needs to consider both surface water and groundwater as a single resource.
Where groundwater extractions exceed recharge, groundwater sustainability needs to be investigated at the planning stage of further developments, including rural-residential development in the council area.
Apart from the Bungendore bore, which has a high groundwater yield, the rest of the council area is within low yield groundwater systems. Local groundwater is mostly found within Palaeozoic rocks or Mesozoic intrusives, and intermediate flows (see About the data) in Precambrian rocks (Bureau of Rural Sciences 2000; Beale et al. 2004). Generally this groundwater is in sedimentary aquifers (Sinclair Knight Mertz 2003).
Although available monitoring networks were insufficient to determine any trends in groundwater levels, modelling of groundwater suggests no significant changes in levels during the reporting period (Beale et al. 2004). In contrast, expert opinion suggests that groundwater levels may have fallen in this reporting period due to reduced rainfall recharge, because of the drought. Natural rainfall is the major variable affecting groundwater recharge (Beale et al. 2004). Recharge would also have been limited by reduced levels of irrigation resulting from restricted surface water conditions.
The council area is entitled to draw 9,096 megalitres of groundwater per year. Private bores in the area are licensed under the NSW Department of Infrastructure Planning and Natural Resources. This groundwater is used mainly for agricultural and domestic purposes.
Council extracted 265 megalitres of groundwater in 2003–04 and 294.5 megalitres of groundwater in 2004–05 for their reticulated urban supply system. It is difficult to provide further reliable data on groundwater use, because generally no other groundwater extractors meter or monitor their groundwater use. This is partly because their water charges are levied on the assumption of full usage of the licensed entitlement (even if the entitlement is not drawn upon).
The western part of Palerang Council Area is associated with groundwater flow systems in the Murray-Murrumbidgee Highlands (Ife and Skelt 2004). In the Highlands, groundwater levels in cleared agricultural landscapes declined as a result of the drought years of the 1990's. At the same time, groundwater levels in discharge areas were still rising, while highland forested areas exhibited no recharge or rising trends (Ike and Skelt 2004). Ife and Skelt (2004) noted that water management planning in the Murrumbidgee catchment needs to consider surface water and groundwater as a single resource.
In order to ensure groundwater sustainability in the longer-term, where extraction exceeds recharge, it has been recommended that further investigation prior to landuse changes be undertaken—particularly in relation to increasing rural-residential developments in the area (Sinclair Knight Mertz 2003).
Much of the groundwater in the council area is of high quality and suitable for drinking (NSW EPA 2000). Some areas yield salt concentrations of 1,000–3,000 milligrams per litre, making it suitable for some domestic, agricultural and limited industrial uses (NSW EPA 2003).
In the general Murrumbidgee catchment, Ife and Skelt (2004) noted high salinity hazards for the Murray-Murrumbidgee Highlands, and that virtually no groundwater quality data were available. The salinity status of two river basins in the eastern half of the council area assessed as part of the NSW Coastal Salinity Audit (Beale et al. 2004) are summarised below:
- Shoalhaven basin
- Groundwater salinity data was patchy. Headwater streams were analysed. The fresh Mongarlowe River carried a salt load of 26 t/km²/year. The catchment above Kado produced a salt load of 13 t/km²/year; large areas of high hazard were identified with only small outbreaks currently known.
- Moruya basin
- Approximately 82% of the basin has been analysed for salt load in two streams, both carrying 22 t/km²/year. Only a very small part of this area has extrapolated groundwater salinity data with high values (3000–5500 µS/cm) located in the lower catchment outside the stream analysis area, but this is not apparently associated with any identified hazard or any known outbreaks. Hazard was identified in the mid-basin but was discounted due to soil type. The salt load analysis, however, suggests that the Deua River had significant salt stores.
No groundwater monitoring results could be obtained for the council area, though EPA licences require monitoring at landfill sites to detect any leakages. Council is in the process of progressively decommissioning its landfills and groundwater monitoring will be part of this process.
Further available data on groundwater contamination in the council area was minimal. There is potential for minor point source contamination resulting from underground petroleum storage and septic tanks. However, cases within the shire are isolated and do not currently pose a serious threat to groundwater quality.
Managing groundwater demand
Water conservation measures
Like surface water, groundwater is considered precious and restrictions were applied where it was pumped for the council-managed reticulated urban supplies. When surface water was under stress the NSW Department of Infrastructure, Planning and Natural Resources reduced groundwater entitlements to licensed extractors.
Laws and policy
Laws recently passed in NSW, such as the Water Management Act 2000 and Catchment Management Authority Act 2003, were aimed in part at ensuring sustainable groundwater extraction. In June 2004, the Council of Australian Governments also targeted efficiency of groundwater systems as part of the National Water Initiative. The western part of the council area falls within the Murray-Darling Basin 'Cap' arrangements and the Murray-Darling Basin Commission's new groundwater management units. For further details of these matters, see Government laws and policies.
In 2002 the NSW Government put in place two new policies—the Groundwater Dependent Ecosystem Policy and the Groundwater Quality Management Policy—to supplement the 1997 Groundwater Quality Protection Policy dealing with allocation, protection and groundwater-dependent ecosystems.
Palerang Council Area falls within the Murrumbidgee and Southern Rivers Catchment Management Authority (CMA) areas. These CMAs set water targets in their Catchment Blueprint 2003–04 (DIPNR 2004); the plans are intended to achieve sustainable groundwater extraction within the 10-year life of the plan. The Southern Rivers CMA Blueprint covers the Shoalhaven River catchment.
To help achieve targets, the Murrumbidgee CMA appointed a Catchment Support Officer to the area with funding from the Natural Heritage Trust.
Water and Coast Management Target 4 in the Southern Rivers Blueprint states that by 2012 primary groundwater management plans will be in place for high use groundwater aquifers systems (DIPNR 2004). The Souther Rivers CMA has also established groundwater management projects (DIPNR 2004) such as targeted awareness programs to bridge gaps in community capacity, Illawarra and Shoalhaven Coastal Land Restoration, and Reduction of Acid Sulfate Discharges into Shoalhaven and Crookhaven Estuaries. All projects were undertaken with Natural Heritage Trust funding.
The extent to which activities under the above reforms affected water management in Palerang Council Area during the reporting period was not assessed for this report.
About the data
Data supplied by Palerang Council and the NSW Department of Infrastructure, Planning and Natural Resources.
Groundwater with less than 1000 milligrams of salt per litre is considered good quality and suitable for drinking water and most uses; groundwater with 1000–3000 milligrams of salt per litre is considered fair to poor and suitable for livestock, some domestic and limited industrial uses (EPA 2000; DLWC 1999).
t/km²/year = tonnes per square kilometre per year
Flow systems—Local groundwater flow systems "have recharge and discharge areas within a few kilometres of one another. They tend to occur within individual subcatchments, in areas of higher relief such as foothills to ranges". Intermediate groundwater flow systems "are intermediate in extent between local and regional systems, generally occurring within individual catchments but also sometimes flowing between smaller subcatchments. They tend to occur in valleys, and typically occur over a horizontal extent of five to ten kilometres" (see Bureau of Rural Sciences 2000, page 4)
Beale G, Miller M, Barnett P, Summerell G, Gilmore R and Hoey D (2004) NSW Coastal Salinity Audit, Department of Infrastructure Planning and Natural Resources, Sydney, online at http://www.dnr.nsw.gov.au/salinity/science/pdf/coastal_audit1.pdf.
Bureau of Rural Sciences (2000) Australian Groundwater Flow Systems Contributing to Dryland Salinity, Bureau of Rural Sciences, Canberra.
Department of Infrastructure Planning and Natural Resources (NSW) (2004) Combined NSW Catchment Management Authorities Annual Report 30003/04, Vol 1: CMA Activities and Achievements, Department of Infrastructure, Planning and Natural Resources, Sydney, online at www.cma.nsw.gov.au and www.dipnr.nsw.gov.au.
Department of Land and Water Conservation (NSW) (1999) Groundwater Quality protection Policy, Department of land and Water Conservation, Sydney, on line at http://www.dnr.nsw.gov.au/water/pdf/nsw_state_groundwater_quality_policy.pdf.
DIPNR—see Department of Infrastructure Planning and Natural Resources (NSW)
DLWC—see Department of Land and Water Conservation (NSW)
Environmental Protection Authority (2000) New South Wales State of the Environment 2000 Report, New South Wales Environmental Protection Authority, Sydney, online at http://www.epa.nsw.gov.au.
Environmental Protection Authority (2003) New South Wales State of the Environment 2003 Report, New South Wales Environmental Protection Authority, Sydney, online at http://www.epa.nsw.gov.au.
EPA—see Environmental Protection Authority
Ife D and Skelt K (2004) Murray-Darling Basin Groundwater Status 1999–2000: Summary Report, Murray-Darling Basin Commission, Canberra, on line at http://www.mdbc.gov.au/nrm/groundwater/groundwater_status_report_19902000.
Sinclair Knight Mertz (2003) Projections of Groundwater Extractions Rates and Implications for Future Demand and Competition for Surface Water, Murray-Darling Basin Commission and CSIRO Australia, Canberra.