Bega Valley
Indicator: Groundwater
Results for this indicator are also available for [an error occurred while processing this directive]
What the results tell us for Bega Valley
Groundwater in the Bega Valley Shire is generally of good to moderate quality and low yield (DLWC 1999), with a steadily decreasing water table (DWE 2008). Good quality groundwater fit for human consumption with little treatment can generally be found along the length of the Shire approximately 20 km inland. Ground water suitable for some livestock, limited domestic and industrial uses can be found closer to the coast.
Groundwater supplies
Groundwater flow in the Shire is mostly from local flow systems in sedimentary Palaeozoic or intrusive igneous Mesozoic rock (DPI 1998).
Bore hydrograph data indicates a consistent seasonally adjusted drop in water levels for the reporting period 2004 to 2008, continuing a trend observed since 1991. A low natural rainfall is likely to be the most significant factor which is further compounded by an increase in extraction (Beale et al. 2004).
Groundwater use
Total groundwater extraction in the Bega Valley is less than 10 GL/yr compared with a natural recharge of more than 500 GL/yr (AWR 2000). Groundwater extraction is low and is considered sustainable for the entire area. However, Bega township (and downstream to the coast) and Eden (and upstream) generally exceed the sustainable level of extraction for the immediate vicinity.
Bega Valley Shire supplies 3.8 GL/yr of water to its customers (DWE 2006) of which 2.1 GL/yr is groundwater sourced from 11 Council bores.
The State Water Corporation (SWC), on behalf of the Department of Water and Energy, administers much of the water allocation in rural NSW. To recover the cost of administration, infrastructure and future investment, the SWC charges each licensed user. In 2007-08, base charges were either $51.46 for non-monitored or $118.56 for monitored areas, plus a per megalitre access charge. As part of the South Coast groundwater area, Bega Valley ground water users are charged a $2.70/ML access charge and $1.35/ML usage charge. Although Bega Shire base charges are the same as other councils throughout the State, Bega shire access and usage charges are the highest in the State (SWC 2008).
Groundwater quality
As part of its obligation under Public Health Act 1991 the Bega Valley Shire Council has an obligation to monitor potable water supplies. Two of Council’s drinking water supplies are sourced from groundwater at Kiah for the Eden township and at Bega for the Bega, Tarraganda, Kalaru and Tathra townships. The potable water monitoring program confirmed excellent reticulated drinking water quality across the Shire. Health Department reports indicate a very high level of public health safety and aesthetic quality of all reticulated water supplied by Council (Bega Valley Shire Council 2007).
Groundwater salinity in the Bega Valley ranges from low to moderate (DLWC 1999). The high altitude interior has a low yield good quality groundwater with less than 1,000mg/L salinity, suitable for human consumption. A coastal strip approximately 20km wide has low quality (1,000-3,000 mg\L salinity) groundwater suitable for livestock and limited domestic and industrial use. The only area recognised as a salinity hazard area is around a 4 km2 region, 20 km SSW of Bermagui (AWR 2000). It is currently rated as moderate hazard. No area within the Shire has been classed as a high salinity hazard for the period up to 2050 (AWR 2005).
Council also monitors localised groundwater quality in association with the following operations:
- effluent reuse at the Shires 10 sewage treatment plants,
- current waste / landfill depots, and
- closed waste landfill depots.
Data from these monitoring operations was not available for this report.
Managing groundwater demand
Water conservation measures
In 2004 the Southern Rivers Catchment Management Authority (SRCMA) was established to guarantee the environmental protection and sustainable development within its area of administration, including impact on water quality and use. Bega Valley is entirely within the boundaries of the SRCMA. With regard to groundwater, the SRCMA has the following water management targets in place (SRCMA 2007) for the Bega Valley:
- By 2008, 80% of priority groundwater will be managed according to a water sharing/management plan.
- By 2016, the quality of priority water bodies will be maintained or progressively improved.
- By 2016, all water utilities will manage water systems consistent with best practices.
- By 2016, residential consumption will progressively be reduced to a set benchmark.
- By 2016, a 20% reduction in water use on 2005 usage by irrigators.
Laws and policy
Outside of regional Catchment Management Authority (CMA) policies, the use and treatment of groundwater is generally the same throughout NSW. Specifically water management and use in the Bega Valley is covered under:
- NSW Water Extraction Monitoring Policy (2007): Designed to increase the extent of active monitoring of water extraction to cover 90% of the total volume of water extracted for each water sharing plan.
- NSW Water Extraction Monitoring Standards (2005): Designed to increase the quality of groundwater extraction monitoring.
- National Water Initiative (2004): NSW is a party to the National Water Initiative (NWI), a national initiative to coordinated Australia's water supply to guarantee the greatest possible social, economic, and environmental benefits.
- NSW NWI Implementation Plan: Addresses the initiatives set out in the NWI specific to the State of NSW.
- Living Murray and Snowy Initiatives (2002): Initiative between Federal and State governments concerned predominately with surface water, however, may indirectly impact on groundwater.
- Water Management Act 2000 (NSW): Aim is to protect the supply of water to the environment and water users. Its introduction has been gradual and once fully implemented will largely supersede the Water Act 1912.
- NSW Groundwater Quality Protection Policy (1998): Aim is largely to protect groundwater resources against pollution.
- Local Government Act 1993(NSW): Covers the quality of water supplied for human consumption by local Council, including groundwater as a source.
- Water Act 1912 (NSW): Largely superseded by the Water Management Act 2000 but some provisions still apply.
- Australian Constitution (1901): Section 100 of the Constitution outlines the States primacy over the Commonwealth in terms of laws and regulations affecting the use and conservation of water.
About the Data
Data was supplied by Bega Shire Council and the NSW Department of Water and Energy. Threshold salinity values of 800 µS/cm and 1,600 µS/cm were used for water quality assessment. They represent the maximum desirable water standard set by the World Health Organisation for human consumption (800 µS/cm) and a threshold at which adverse environmental changes can be expected (1,600 µS/cm) (NHMRC and ARMCANZ 1996).
Groundwater with less than 1000 mg of salt per litre is also considered good quality and suitable for drinking water and most uses; groundwater with 1000–3000 mg of salt per litre is considered fair to poor and suitable for livestock, some domestic and limited industrial uses (DLWC 1999).
mg/L = milligrams per litre
References
Australian Water Resources (2000) National Land and Water Audit.
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.
Bega Valley Shire Council 2007 (NSW) (2007) Annual Report, online at http://www.begavalley.nsw.gov.au/Your_Council/Annual%20Report/Annual_Report.htm
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.
Department of Land and Water Conservation (NSW) (2001) Groundwater Vulnerability Map and Explanatory Notes, Department of Land and Water Conservation, Sydney, on line at http://www.dnr.nsw.gov.au/water/pdf/lachlan_vulnerability_map.pdf.
Department of Primary Industries (NSW (1998) Geological Map of New South Wales (1:250000 scale)
Department of Water and Energy (NSW (2006) 2005/06 Water Supply and Sewage Benchmarking Report on line http://www.deus.nsw.gov.au/Publications/dwe_nsw_water_supply_and_sewerage_benchmarking_report_2005-06.pdf
Department of Water and Energy (NSW (2008) – Bore Location Information supplied in GIS format.
NHMRC and ARMCANZ (1996) Australian Drinking Water Standards, National Health and Medical Research Council & Agricultural Resources Management Council of Australia and New Zealand, Canberra.
State Water Corporation (NSW) (2008) Water Management Charges for Licensed Water Users on line http://www.statewater.com.au/watdel/water_mgt_charges_for_licensed_water_20080124.pdf
Southern Rivers Catchment Management Authority (NSW) (2007) SRCMA Annual Report 2006/2007 online at http://www.southern.cma.nsw.gov.au/pdf/SRCMA_AR2007body.pdf
