Young Granite Groundwater Source · The Young Granite groundwater source is now managed under the...

Young Granite Groundwater Source Status Report 2012

Publisher: NSW Department of Primary Industries, Office of Water


First published March 2013

ISBN 978 1 74256 482 1

This publication may be cited as:

Kumar, P. B., (2013) Young Granite Groundwater Source Status Report 2012, NSW Office of Water, Sydney

More information

www.water.nsw.gov.au

Acknowledgments

Cover image: Irrigated orchard near Wombat by Megan Purvis, NSW Office of Water, Wagga Wagga

Jobtrack 11962

© State of New South Wales through the Department of Trade and Investment, Regional Infrastructure and Services 2013. You may copy, distribute and otherwise freely deal with this publication for any purpose, provided that you attribute the NSW Department of Primary Industries as the owner.

Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (March 2013). However,

because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency

of the information with the appropriate officer of the Department of Primary Industries or the user’s independent adviser.


Executive summary

This report describes the status of groundwater resources within the Young Granite groundwater source located around Young within the southwest slopes region of New South Wales. The groundwater water source covers an area of approximately 71,500 hectares or 715 km2.

The area receives an average annual rainfall of 650 mm/year with mean annual evaporation rate of about 1,390 mm. The mean monthly rainfall ranges 44-64 mm with slightly higher averages during the months June to December.

Livestock grazing is the dominant land use within the water source together with dryland cropping and smaller more intensively irrigated areas of horticulture.

The Young Granite groundwater source is within the Young Granodiorite of Late Silurian age which forms part of the much larger NSW Lachlan Fold Belt complex. Water bearing zones within the groundwater source are generally associated with fractures and weathered zones within the granodiorite body. Existing bore data indicate weathering depths of about 30 m with fractures extending to depths greater than 80 m. The average yield for a bore in the water source is about 4 L/s however yields of up to 50 L/s have been obtained in some bores.

The Young Granite groundwater source is now managed under the Water Management Act 2000 following the implementation of the NSW Murray-Darling Basin Fractured Rock Groundwater Sources water sharing plan in January 2012. The estimated average annual recharge and environmental water at the beginning of the plan was 18.9 GL/yr and 9.5 GL/Yr respectively. Under the Plan groundwater extraction is managed to the long-term average annual extraction limit set at 9.5 GL/yr. There were 136 access licences with total shares of 6.3 GL at the commencement of the Plan.

There are 167 production bores for irrigation within the water source and with an estimated 80-90% without meters. Groundwater usage is estimated largely from information provided by licence holders. A maximum usage of 1.9 GL was recorded in 2002/03 during the early part of the decade-long drought. Much lower usages (0.5 GL) have been recorded over the last two years due to the recent wet conditions.

Groundwater levels within this fractured rock water source show a strong correlation with rainfall indicating it to be the dominant recharge source. Groundwater levels have generally declined over the period 2006-2009 with marked rises at the beginning of 2010. The recovered water levels in all the monitoring bores are higher than levels observed at the beginning of the record.

i NSW Office of Water, January 2013


ii NSW Office of Water, March 2013

Contents Executive summary.........................................................................................................................i

1. Introduction ................................................................................................................................1

2. Topography and climate.............................................................................................................1

3. Geology and hydrogeology ........................................................................................................ 5

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3.1 Regional geology..................................................................................................................

3.2 Hydrogeology .......................................................................................................................

4. Groundwater management ......................................................................................................

4.2 Current management framework........................................................................................

4.3 Definition of Young Granite groundwater source................................................................

4.4 Plan provisions ...................................................................................................................

4.4 Available water determination (AWD).................................................................................

4.6 Existing access licences.....................................................................................................

4.7 Access licences and trades ................................................................................................

5. Resource monitoring ................................................................................................................

5.1 Groundwater usage ............................................................................................................

5.2 Groundwater levels.............................................................................................................

5.2.1 Murrumbidgee River catchment...................................................................................

5.2.2 Lachlan River catchment .............................................................................................

5.3 Groundwater quality ...........................................................................................................

6. Conclusions..............................................................................................................................

References...................................................................................................................................

Appendix A: Lithology logs for monitoring bores..........................................................................

Appendix B: Hydrographs for bores GW090075, GW090081, GW090082 and GW403607 .......

Appendix C: Groundwater chemistry data ...................................................................................


iii NSW Office of Water, March 2013

Tables Table 1 Aquifer characteristics....................................................................................................... 6

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Table 2 Groundwater management history..................................................................................

Table 3 Water sources established in the Plan............................................................................

Table 4 Plan provisions................................................................................................................

Table 5 Existing access licences .................................................................................................

Table 6 Access licence account and trade rules..........................................................................

Table 7 Summary of groundwater chemistry ...............................................................................

Figures Figure 1 Location Map ...................................................................................................................

Figure 2 Dryland farming................................................................................................................

Figure 3 Irrigated vineyard .............................................................................................................

Figure 4 Average monthly rainfall at Young ...................................................................................

Figure 5 Cumulative deviations from mean monthly rainfall ..........................................................

Figure 6 Geology map....................................................................................................................

Figure 7 Total magnetic intensity image ........................................................................................

Figure 8 Simplified NSW Major Fold Belts Map .............................................................................

Figure 9 Granodiorite outcrop ......................................................................................................

Figure 10 Comparison of surface elevations and groundwater levels .........................................

Figure 11 Location of pumping bores...........................................................................................

Figure 12 Groundwater usage .....................................................................................................

Figure 13 Monitoring bore locations.............................................................................................

Figure 14 Hydrograph for groundwater monitoring site GW403610 (Ventor Road, Karuah) .......

Figure 15 Hydrograph for groundwater monitoring site GW403609 (Pine Road, Anfield Park)...

Figure 16 Hydrograph for groundwater monitoring site GW403606 (Allambie Orchard) .............

Figure 17 Hydrograph for groundwater monitoring site GW403611 (Back Creek Road).............

Figure 18 Hydrograph for groundwater monitoring site GW090077 (south of Young).................

Figure 19 Hydrograph for groundwater monitoring site GW090080 (northeast of Young)...........

Figure 20 Electrical conductivity of groundwater in monitoring bores within Young Granite groundwater source .....................................................................................................................


1. Introduction

This report presents the status of groundwater resources within the Young Granite groundwater source (hereafter referred as YGGWS) centred near the township of Young (Figure 1) within the southwest slopes region of New South Wales (NSW). The water source covers an area of approximately 71,500 hectares or 715 km2 and straddles the Lachlan and Murrumbidgee surface water catchments.

Water Sharing Plans are being developed for all groundwater sources in NSW following the introduction of the Water Management Act 2000 (WMA 2000). The plan for NSW Murray-Darling Basin Fractured Rock Groundwater Sources (hereafter referred as the Plan) commenced on 16th January 2012. A copy of the Plan can be viewed on the NSW legislation website www.legislation.nsw.gov.au. It applies to a number of specific aquifers or a series of aquifers of similar characteristics (e.g. fractured rock) within inland NSW including the YGGWS. The Plan provides for the sharing of water between the environment, town water supplies, commercial and basic landholder rights (BLR) users.

Groundwater within the YGGWS is generally of very good quality and has been developed mainly for domestic and stock and small irrigation supplies.

2. Topography and climate

The area is characterised by smooth, rounded and gently undulating hills and valleys exhibiting typical granite topography. Ground elevations range approximately 400-550 metres AHD (Australian Height Datum or approximately metres above sea level).

There are no major rivers within the YGGWS. Most of the water source area lies within the Lachlan surface water catchment and is drained to the north by Burrangong and Cudgell creek systems. A smaller area of the YGGWS falls within the Murrumbidgee surface water catchment and is drained to the south by the Demondrille and Moppity creeks. These are small ephemeral creeks that only flow following periods of high rainfall.

Livestock grazing is the dominant land use within the plan area together with dryland (canola and wheat mainly) and smaller areas of irrigated (grapes and stone fruits mainly) cropping (Figures 2 and 3).

The area experiences warm summers with cool to cold winters and receives an average annual rainfall of 650 mm/year. The mean monthly rainfall ranges 44-64 mm with slightly higher averages during the months June to December (Figure 4).

No evaporation data is available for Young. However, data from nearby Cowra (Station No. 63023) indicate mean evaporation rate of approximately 1,390 mm/yr.

Figure 5 shows the cumulative deviation from mean monthly rainfall for Young. The upward or downward slope of this graph is indicative of wet or dry conditions experienced at Young compared to the average for the period of the record.

The graph shows a fairly lengthy period of less than average rainfall conditions during 1895-1947 followed by a wetter (or above average rainfall) conditions until1976. Over the last five decades the dry or below average rainfall was again evident during 1976-1983 and 2001-2009. The change in slope late in 2009 is indicative of the change to fairly wet conditions experienced recently over the last two years.

1 NSW Office of Water, March 2013

http://www.legislation.nsw.gov.au/


Figure 1 Location map



Figure 2 Dryland farming

Figure 3 Irrigated vineyard



Figure 4 Average monthly rainfall at Young

Average Monthly Rainfall Young (1870-2011)

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Station 73056 (Young Post Off ice, 1872-1991)

Station 73138 (Young Airport, 1994-present)



3. Geology and hydrogeology

3.1 Regional geology The geology of the area is shown on Figure 6. The Young Granodiorite can be described as a large, elongate, north to northwest trending batholith, extending from the north near Greenethorpe (east of Grenfell) to Talbingo southeast of Tumut. It is part of the larger Lachlan Fold Belt complex also known as the Lachlan Orogen which is a geological subdivision of the eastern part of Australia. It is a zone of folded and faulted rocks of Late Cambrian (500 million years) to Early Carboniferous (360 million years) age that has undergone several stages of deformation during its evolution (Kingham, 1998). The emplacement of the granodiorite body occurred during Silurian and Devonian periods (440-360 million years).

The eastern boundary of the Young Granodiorite is irregular and intrusive into the Duoro Volcanics (Hervey Group) whereas complex thrust faults (Thuddungra Fault and Mooney Mooney Fault Zone) forms the western boundary. A number of generally north-south trending lineaments (magnetic lineaments) exist within the Lachlan Fold Belt including the granodiorite body (Figure 7). Most of these structures (or lineaments) are not apparent from traditional geological mapping.

The Young Granodiorite has been described as a coarse-grained, grey, and massive to foliated, biotite granodiorite that grades to quartz monzonite (Basden et al., 1978). It hosts significant gold mineralisation near Young, Wombat and Harden-Murrumbarrah areas. These are located mainly in areas to the north and east of Jugiong Shear Zone and are associated with the north to northwest trending structures (Downes et al., 2004).

Prolonged weathering of the granodiorite has been significant in the development of shallow aquifer (weathered granodiorite and alluvium) as well as deposition of minerals. Thin Quaternary alluvium associated with existing creeks overlies the Young granodiorite. These are known through previous gold mining activity in the region (Williams, 1983).

3.2 Hydrogeology The YGGWS is defined as a fractured rock aquifer. Groundwater in such aquifers is normally stored and transmitted through fractures, joints, faults and cavities within the rock mass. The ability of such an aquifer to transmit reasonable quantities of water largely depends on the interconnection of these generally higher permeability features. Groundwater flow is often strongly influenced by the orientation of such features rather than the distribution of heads. Weathering can also play a significant role in the development of such an aquifer.

The YGGWS incorporates a small portion of the Young Granodiorite that outcrops in areas to the east of the Thuddungra fault zone and north of Harden (Figure 8). Water bearing zones within the granodiorite body is generally associated with weathering, especially in heavily fractured and faulted zones that has led to the development of secondary porosity and permeability.

There are about 167 production bores for irrigation within the water source and a significant proportion of these (at least 38%) are constructed to depths greater than 80 m with the deepest bore constructed to a depth of 295 m. Data from these bores (driller’s log) indicate an average weathering depth of 28 m compared to the average construction depth of 79 m. In addition to this, there are about 393 stock and domestic bores with an average depth of about 59 m. This suggests that water bearing zones associated with fractures extend well beyond 28 m to depths greater than 80 m.

Recharge to the groundwater source occurs primarily through infiltration from rainfall and runoff. It occurs mostly on hilltops and slopes where weathered sequences are likely to be thin or absent (Figure 9). Discharge occurs in localised areas at the break-of-slope, at lateral changes in soil texture and in the bases of some valleys (CSIRO, 2008).




There are several small creeks within the water source, most are ephemeral and do not receive any significant baseflow (CSIRO and SKM, 2010).

The Quaternary alluvium, consisting of clay, silt, sand and gravel associated with existing creeks within the water source, may also contain groundwater. Occasional low yielding bores are constructed within this alluvium.

The boundary for Lachlan and Murrumbidgee catchments located south of Young forms the surface drainage divide. Although influenced by fractures (etc.) groundwater flow appears to follow the topography and flows both north and south of this catchment divide. This is further indicated from the relatively good correlation between surface elevation and recovered groundwater levels (or July levels) in 7 bores (all within the Murrumbidgee catchment) when compared in metres AHD (Figure 10).

The aquifer characteristics of the YGGWS are summarised in Table 1.

Table 1 Aquifer characteristics

Description Young Granite Groundwater Source

Geological age of aquifer material Middle to Late Silurian

0-80 m 62 % of all of pumping bores constructed to depths <80 m variable bore yield, range 0.2-15 L/s average bore yield of 2.3 L/s maximum bore yield 15 L/s does not include information from stock & domestic bores

Description of water bearing zones >80 m 38 % of all pumping bores constructed to depths >80 m bore depths range 81-295 m variable bore yield, range 0.1-48 L/s average bore yield of 7.8 L/s maximum bore yield 48 L/s does not include information from stock & domestic bores

Yields (L/s) based on all pumping bores (irrespective of depth) variable 0.1 - 48 average yield of 4.3

Water quality (electrical conductivity in µS/cm)

from departmental monitoring bores range 470 -3,200

Depth to groundwater (m below ground)

-2 (flowing) to 50

Aquifer type 0-20 m – unconfined to partially confined >20 m – partially confined to confined

Hydraulic conductivity estimate (m/d) Variable 0.1 -2.0

Specific Yield/Storage Coefficient (estimate only)

1x10-1 – 1x10-4

Groundwater flow direction

generally to the north (in areas north of the Lachlan/Murrumbidgee catchment divide) generally to the south (in areas south of the divide)


Figure 6 Geology map



Figure 7 Total magnetic intensity image



Figure 8 Simplified NSW major fold belts map



Figure 9 Granodiorite outcrop

Figure 10 Comparison of surface elevations and groundwater levels

Young Granite Groundwater Source

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4. Groundwater management

The history of groundwater management and key policy development for the YGGWS is summarised and provided in Table 2.

Table 2 Groundwater management history

Period Description Source

1955 Construction of all bores in NSW required a licence. Groundwater licences for irrigation were unrestricted in volume and issued in perpetuity.

Gates & O’Keefe 1997

1972-1992 Licences for irrigation became renewable on a 5-year basis and were issued initially based on property size and later on area of irrigation. Licences for town water supply, mining and commercial activities were issued on a needs basis.

Gates & O’Keefe 1997

1992 New groundwater licences were issued on irrigation requirement of 6 ML/Ha but capped to a property ceiling of 243 ML/yr.

DLWC 2000

1999

A policy for fractured rock was developed based on percentage of rainfall recharge (0.5 ML/Ha) and capped to 30 ML per bore unless higher yields were proven through pumping tests. Meters were required for all bores licensed to extract volumes greater than 8 ML/yr.

Carter et al. 1999

2003 An embargo on new commercial licence applications was introduced on 19th May due to the intensity of existing bores and entitlements exceeding the estimated sustainable yield.

DIPNR 2003

2008 A state-wide embargo on new commercial groundwater licence applications introduced on 4th July 2008.

DWE 2008

2009 A state-wide groundwater trading policy for inland aquifers was introduced in August 2009 allowing temporary groundwater trading within the YGGWS.

DWE 2009

2012 The water sharing plan for NSW Murray-Darling Fractured Rock Groundwater Sources commenced on 16th January, 2012.

Office of Water 2012

Prior to 2012 groundwater within the YGGWS was managed under the Water Act 1912.

4.2 Current management framework Development of water sharing plans for surface water and groundwater systems under the WMA 2000 first commenced in 2001 and were finalised during the period 2004-2008. These initial plans mainly covered the major regulated rivers systems and their associated major alluvial aquifers and some unregulated systems. In 2004, the development of plans using the “macro” water sharing plan approach for the remaining aquifers commenced. Macro plans are water sharing plans that cover large areas and apply to a number of water sources of similar types (e.g. fractured, porous or alluvial) and may span across catchments. The macro plans include generic rules that apply to all groundwater users together with specific rules for particular areas (or water sources) thus providing flexibility to manage local issues. The Plan for NSW Murray-Darling Basin Fractured Rock Groundwater Sources commenced on 16th January 2012 and established ten separate groundwater sources including the YGGWS (Table 3) and provides a legislative basis for the sharing of water between the environment and consumptive users within the water sources. A copy of the plan can be viewed on the NSW legislation website www.legislation.nsw.gov.au.

This change in management means that groundwater access licences are now held under separate title to the land and are issued in perpetuity. Under this new arrangement groundwater may be extracted for domestic and stock purposes (basic landholder rights) without an access licence. However, an approval for a bore is required from the NSW Office of Water.

The Plan defines access rules for period of ten years (duration of plan) and ensures that groundwater extraction is managed to the long-term average annual extraction limit (LTAAEL) of the groundwater source.


http://www.legislation.nsw.gov.au/


Table 3 Water sources established in the plan

Water Source Management Zone

Adelaide Fold Belt MDB none

Inverell Basalt none

Kanmantoo Fold Belt MDB none

Lachlan Fold Belt MDB (Mudgee) Lachlan Fold Belt MDB

Lachlan Fold Belt MDB (Other)

Liverpool Ranges Basalt MDB none

New England Fold Belt MDB none

Orange Basalt none

Warrumbungle Basalt none

Yass Catchment none

Young Granite none

4.3 Definition of Young Granite groundwater source Under the Plan the YGGWS is defined as groundwater contained in all rocks and alluvial sediments within the boundary of the water source. The water source area includes the parishes of Baxter, Burrangong, Moppity, Thuddungara, Wambat, Wilkie, Young and parts of Marina and Woodonga (Figure 1) in the Counties of Monteagle and Harden.

4.4 Plan provisions The Plan uses long-term average annual recharge as the basis for water sharing. The recharge, environmental water, extraction requirements and limits for YGGWS are provided in Table 4. The annual extraction limit for the YGGWS is set at 9.53 GL/year.

Table 4 Plan provisions

Provisions Volumes (ML/yr)

Average annual rainfall recharge over areas that are not of high environmental value

19,058

Average annual rainfall recharge over areas that are of high environmental value

5

Total rainfall recharge over water source area 19,063

Amount of annual recharge set aside as environmental water1

9,534

Basic landholder rights 759

Native titles rights 0

LTAAEL2 9,529

1. The volume of recharge set aside as environmental water for YGGWS is made up of 50% of average annual recharge generated over areas that are not of high environmental value and 100% of recharge generated over areas of high environmental value. 2. The LTAAEL for YGGWS is set at 50% of recharge volume generated over areas that are not of high environmental value.

Groundwater sources generally store large volumes of water and the amount of annual recharge is often relatively small compared to the stored volume. The existing Plan does not allow access to the storage component of the fractured rock groundwater sources over the long-term thus protecting its depletion due to extraction.



4.4 Available water determination (AWD) At the beginning of each water year the allocation of water for each category of access licence is made under the Plan by an Available Water Determination. At the start of the Plan these were set at 1ML/share for all licence categories. The Plan requires these to be reduced if annual extractions, averaged over the preceding three water years, exceed the extraction limit by 5% or more. Assessments for reductions in the Available Water Determinations will commence in the fourth year of the plan.

Growth in extraction (or usage) will be managed through a reduction in allocation (from 100 per cent) for aquifer access licences in the water source. It will be reduced by an amount necessary to return total water extractions within the water source down to the extraction limit.

4.6 Existing access licences The existing access licences within the YGGWS at the beginning of the plan are summarised in Table 5 below.

Table 5 Existing access licences

Licence Category Number Volume (ML/yr)

Access Licences 135 6,338

Local Water Utility 1 16

total 136 6,354

Individual licence shares (or entitlement) range from 2-456 ML with 73 licences (or 54%) have shares of less than 20 ML. In addition to these there are over 600 approvals for stock and domestic (or basic landholder rights) bores.

4.7 Access licences and trades The following groundwater trades (or dealings) are permitted under the plan:

sale or transfer of the ownership of an access licence (71 M dealing);

lease (or rental) of an access licence known as term transfer (71N dealing);

sub-division or consolidation of access licences (71P dealing);

sale of the share component (or assignment) of an access licence commonly known as permanent trade (71Q dealing);

sale of account water or assignment of water allocation commonly known as temporary trade (71T dealing); and

change in the location within the water source from where a work (or bore) can extract water held under an access licence (71W dealing).

The rules for managing access licence accounts and trades are summarised in Table 6.




Table 6 Access licence account and trade rules

Rules

Trades Both temporary and permanent trades between access licences within the water source are permitted. Trade between water sources is not permitted (e.g. licence within YGGWS cannot trade to or from licences within Orange Basalt, Yass Catchment or LFB MDB or other fractured rock water sources). All trades are subject to assessment of third party impacts.

Carryover1 Carryover is limited to 10% of share component (or 0.1 ML per unit share of access licence share component). No carryover is allowed for domestic and stock, local water utility or special purpose access licences.

Take Limit2 The maximum amount of water permitted to be taken in any one water year is the water allocation accrued in the access licence account for that water year including carryover from the previous year, adjusted for allocation assignments (trades) out of or into individual licence accounts.

1. Carryover is the maximum amount of unused account water that can be carried over from one water year to another. Zero share access licences do not have any provisions for carryover. 2. Take Limit is the volume of account water that can be extracted or traded out when available.


5. Resource monitoring

Groundwater level monitoring within the YGGWS commenced in 2006 with the first monitoring bores constructed in late 2005. The level of monitoring in the water source has since improved with regular monitoring of both groundwater levels and extractions.

Following the implementation of the plan licence holders are being advised to install meters to all bores that extract water held under access licences (i.e. those used for purposes other than stock and domestic). This will improve the level of metering (or usage monitoring) including compliance with metering conditions within the groundwater source.

5.1 Groundwater usage There are about 167 pumping bores associated with access licences within the YGGWS (Figure 11). A large number of these (approximately 80-90 %) still do not have meters hence actual use is not reliably known. Reported extractions are based on information provided by users and likely to be an under estimate of actual use. Many of these bores are also used for stock and domestic purposes.

The recorded extractions since 1997 are provided in Figure 12. A marked rise in groundwater usage in 2002/03 is evident. The observed increase in extraction is due to the generally dry conditions observed during the period 2001-10 with 2002 being a fairly dry year with less than 400 mm of rainfall. However, it may also reflect improved level of monitoring. The decline in usage after 2010 is due to the wet conditions experienced recently.

There are approximately 400 constructed domestic and stock bores in the water source. The locations are shown on Figure 11.

5.2 Groundwater levels There are 10 monitoring sites within the YGGWS (Figure 13) with monitoring only commencing relatively recently in late 2006.

5.2.1 Murrumbidgee River catchment

Figures 14-17 show variations in groundwater levels in monitoring bores located south of Young within the Murrumbidgee River surface water catchment portion of YGGWS. The hydrographs show variations in water levels (presented as metres below surface) in monitoring bores at specific depth intervals below surface. These are shown as screen intervals on the hydrographs and represent the water bearing zone(s) within the water source at that location. The cumulative deviation from the average monthly rainfall is also shown. Groundwater levels in all 5 monitoring bores show strong correlation with rainfall. The wet years of 2010 and 2011 have caused significant groundwater level rises at all sites indicating the occurrence of rainfall derived recharge during the period.

Monitoring site GW403610 is located in Kingsvale just southeast of Wombat (Figure 13) in an area developed extensively for horticulture. There are seven pumping bores located within a km from this site with the closest only 150 m away. The hydrograph for this monitoring bore (Figure 14) shows large, up to 12 m seasonal fluctuations due to its close proximity to pumping bores. Water levels have recovered by more than 10 m since winter of 2009 over a period of above average rainfall conditions and lower pumping. The recovered level is about 6 m higher than those measured in October 2006 at the beginning of monitoring. The levels in the shallow aquifer are higher than the deeper levels indicating a downward vertical gradient (i.e. flow from shallow to deep).



Figure 11 Location of pumping bores



Figure 12 Groundwater usage

Young Granite

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GW403609 is located only 1.2 km to the southeast of GW403610 but shows little influence (or seasonal variation) from nearby pumping (Figure 15). This is most likely due to low levels of pumping and greater distance (approx. 500 m) from neighbouring bores. The recovered level at this site is about 0.5 m higher than those measured in October 2006 at the beginning of monitoring. It is noted that this bore has been flowing for a period of 3-4 months during January-March 2011 and April-July 2012. These are periods following months of higher than average rainfall.

GW403606 is located just north of Wombat in an area with a relatively small number of orchards and fewer pumping bores, the closest about 650 m away. As expected, the hydrograph for this monitoring bore (Figure 16) shows little influence from nearby pumping. Water levels in both shallow and deep pipes show recovery of about 2.5 m since mid 2010. The recovered levels are slightly higher than levels at the beginning of the record. The levels in the deep aquifer are slightly higher than the shallow levels indicating a small upward gradient (i.e. flow from deep to shallow).

GW403611 is located about 7.5 km northeast of Wombat on the southern side of the catchment divide. The closest pumping bore is only 50 m away but its impact has not been observed possibly due to low level of pumping. The hydrograph (Figure 17) shows recovery of about 2.7 m since 2010. As noted previously the recovered levels are slightly higher than levels at the beginning of the record.



Figure 13 Monitoring bore locations



Figure 14 Hydrograph for groundwater monitoring site GW403610 (Ventor Road, Karuah)

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Figure 15 Hydrograph for groundwater monitoring site GW403609 (Pine Road, Anfield Park)

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Figure 16 Hydrograph for groundwater monitoring site GW403606 (Allambie Orchard)

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Figure 17 Hydrograph for groundwater monitoring site GW403611 (Back Creek Road)

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5.2.2 Lachlan River catchment

Figures 18 and 19 show variations in groundwater levels in monitoring bores located within the Lachlan River surface water catchment portion of YGGWS. The hydrographs show variations in water levels (presented as m below measuring point) in monitoring bores at specific depth intervals below ground. The five bores were constructed in 2005 as part of a groundwater monitoring project funded by National Action Plan for Water Quality and Salinity. Groundwater levels in all 5 monitoring bores show strong correlation with rainfall. As noted previously the wet years of 2010 and 2011 have caused significant rises in groundwater levels at all five sites indicating that recharge to groundwater is occurring predominantly from rainfall.

GW090077 is located about 7.5 km northeast of Wombat on the northern side of the catchment divide. The pumping bores in the area are generally located to the south and southwest of the monitoring site. Seasonal fluctuations due to pumping are not apparent (Figure 18).

GW090082 is located approximately 9 km to the northwest of Young near the settlement of Maimuru. Pumping bores are located to the northwest and southeast with none within 2 km of the monitoring site. Groundwater level variations observed (Figure 19) are natural and show little influence from local pumping.

The hydrographs from other sites show a similar response and are provided in Appendix B.

Figure 18 Hydrograph for groundwater monitoring site GW090077 (south of Young)

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Figure 19 Hydrograph for groundwater monitoring site GW090080 (northeast of Young)

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5.3 Groundwater quality There is no dedicated program for groundwater quality monitoring within the YGGWS. Most of the domestic and stock and irrigation bores do not have electrical conductivity (EC) or salinity information. However, the available information from Office of Water’s monitoring bores indicates that groundwater within the water source has EC’s ranging 470-3,200 µS/cm. Groundwater chemistry data from the five monitoring bores is available and provided in Appendix C. Smithson (2005) describes the hydrochemistry in detail. A brief summary of the analysis is provided in Table 7.

Groundwater chemistry is similar at all five monitoring sites located within the Lachlan catchment portion of YGGWS with sodium and chloride as the dominant ions. The groundwater within YGGWS is expected to be young and fairly fresh given that the area receives a relatively higher rainfall of about 650 mm/year.

The remaining YGGWS monitoring bores located in the Murrumbidgee catchment to date do not have water quality information. These bores were sampled for major ion analysis in October 2012. The laboratory results were not available at the time of reporting. The field EC measurements from this sampling event are reported in Table 7 and shown on Figure 20.

Further sampling and analysis from all monitoring bores and some selected pumping bores is required to fully understand the groundwater chemistry and its evolution along the groundwater flow paths.



Table 7 Summary of groundwater chemistry

GW Number Pipe

Number Completed Depth (m)

Screened interval (m)

Date Sampled Electrical

Conductivity (µS/cm)

Groundwater Type

GW090075 1 24 20.3-22.3 Nov 2005 649 Na-HCO3-(Cl)

GW090077 1 7 3-5 Nov 2005 466 Na-(Mg)-Cl-(HCO3)

GW090077 2 50 44-47 Nov 2005 815 Na-(Ca)-HCO3-(Cl)

GW090080 1 8 4-6 Nov 2005 dry during sampling

GW090080 2 50 44-47 Nov 2005 1,933 Na-Cl-(HCO3)

GW090081 1 8 4-6 Nov 2005 2,631 Na-Cl-(HCO3)

GW090081 2 21 15-21 Nov 2005 3,160 Mg-Ca-Na-Cl-(HCO3)

GW090082 1 8 4-6 Nov 2005 740 Na-Ca-(Mg)-HCO3

GW090082 2 40 28-34 Nov 2005 590 Ca-Mg-(Na)-HCO3-Cl

GW403606 1 28 22-28 Oct 2012 799 not analysed

GW403606 2 63 57-63 Oct 2012 556 not analysed

GW403607 1 96 56-58 Oct 2012 1,524 not analysed







Figure 20 Electrical conductivity of groundwater in monitoring bores within Young Granite groundwater source



6. Conclusions

The key conclusions regarding the YGGWS are highlighted below.

Water bearing zones within the YGGWS are associated with fractures (joints and faults) and degree of weathering.

Data from bores suggest a weathering depth of approximately 30 m and that water bearing zones associated with fractures extend beyond 80 m.

Groundwater flow is strongly influenced by topography although the orientation of lineaments such as fractures, faults and dykes may also play a significant role.

The Quaternary alluvium associated with existing creeks within the water source only contains occasional low-yielding bores. It is not a significant source for groundwater supply.

Groundwater level and rainfall data indicate that recharge to the water source occurs primarily through infiltration from rainfall and runoff.

Groundwater within the YGGWS is generally fresh with electrical conductivity values ranging 470-3,200 µS/cm.

Very limited groundwater quality data is available. Further groundwater quality monitoring is required to fully understand the hydro-geo-chemistry of the water source.

Water levels in all monitoring bores have recovered to levels shallower than those at the beginning of the monitoring record in October 2006. This is due largely to the observed relatively wet conditions over the last two years together with low levels of groundwater extraction.

Groundwater trading between access licences within the YGGWS is permitted. However, trading between access licences in different groundwater sources (e.g. between YGGWS and Yass Catchment licences) are not permitted under current rules.

The current estimated usage is well below the total licensed share volume (or entitlement). However, it should be noted that groundwater extraction within YGGWS is not reliably known as a large number of bores (80-90%) are still unmetered and that the reported usage is largely based on information provided by licence holders.




References Basden, H., 1974. Preliminary report on the geology of the Cootamundra 1:100 000 sheet. Geological

Survey of New South Wales, Quarterly Notes 46, 1-18.

Basden, H., Adrian, J., Clift, D.S. L., and Winchester, R. E. 1978. Geology of the Cootamundra 1:100,000 Sheet 8528. Geological Survey of New South Wales, Sydney, 276 pp.

Carter, A., 2000. Upper Murrumbidgee Groundwater Status Report, NSW Land and Water Conservation Technical Report No. 99/03, ISBN No: 0 7313 5340 4.

CSIRO 2008. Water availability in the Lachlan. A report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project. CSIRO, Australia.133pp.

CSIRO and SKM 2010. Sustainable extraction limits derived from the Recharge Risk Assessment Method – New South Wales (part 2). CSIRO: Water for a Healthy Country Flagship. 84 pp.

DLWC 1999. Draft Murrumbidgee bore licensing procedures and policy summary. Supporting information for hydrogeological review of bore licence applications April 1999.

DLWC 2000. Summary of Groundwater Management Procedures and Information for Central West Region, Report No. CW-GWS 2000/15. March 2000.

DIPNR 2003. Department of Infrastructure Planning and Natural Resources. New South Wales Government Gazette, Number 89. 23 May, 2003.

Downes, P., M., McVilly, R. and Raphael, N., M., 2004. Mineral deposits and models, Cootamundra 1:250 000 map sheet area. Geological Survey of New South Wales, Quarterly Notes 116, 1-38.

Gates, G., and O’Keefe, V., 1997. A brief paper on groundwater management in NSW. Department of Land and Water Conservation (unpublished).

http://en.wikipedia.org/wiki/Lachlan_Fold_Belt

Kingham, R.A., 1998. Geology of the Murray-Darling Basin-Simplified Lithostratigraphic Groupings. Australian Geological Survey Organisation, Record1998/21.

NSW Office of Water 2011, Water sharing plans - Inland NSW groundwater sources – Overview, NSW Office of Water, October 2011.

NSW Office of Water 2012, Water Sharing Plan for the Murray-Darling Fractured Rock Groundwater Sources – Background document, NSW Department of Primary Industries, NSW Office of Water, January 2012.

Smithson, A., 2007. Groundwater Monitoring Project: Lake Cargelligo and Young, Lachlan Catchment, Central NSW. National Action Plan for Water Quality and Salinity Project LA0005. NSW Department of Natural Resources, Groundwater Unit, Water Management Division.

Williams, R.M., 1983. Hydrogeology and Hydrochemistry of the Young Granodiorite in the Vicinity of the Young Township, NSW. Water Resources Commission, Sydney. Report No. 1983/7.

Williams, R.M., 1990. Groundwater Conditions in the Young (Scenic Road) Land Care Group Area. Technical Services Division, NSW Department of Water Resources, Sydney. Report No. TS90.044, ISBN 0 7240 3844 2.

http://en.wikipedia.org/wiki/Lachlan_Fold_Belt


Appendix A: Lithology logs for monitoring bores

Monitoring Bore GW090075

From depth (m)

To depth (m)

Description (Geologist’s log) Rock type

0 1 Stiff, dark red silt (parna?), contains minor fine sub-rounded quartz grains up to 2mm ex-granite.

1 2 Stiff, orange silt (parna?), contains minor fine sub-rounded quartz grains up to 2mm ex-granite.

2 3 Stiff, orange, slightly micaceous clayey silt.

SILT

3 7 Firm, pink, extremely weathered, slightly micaceous granite.

7 16 Firm, orange, highly weathered, slightly micaceous granite.

16 25 Firm, orange, moderately weathered, slightly micaceous granite.

GRANITE


From depth (m)

To depth (m)


0 2 Soft, (powdery) pale orange, extremely weathered, slightly micaceous granite.

2 6 Firm, orange-tan, highly weathered, granite.

6 7 Soft, dark brownish orange, clayey, highly weathered granite.

7 9 Soft, orange-grey, clayey, highly weathered granite.

9 10 Firm, greyish-orange, moderately weathered, granite.

10 11 Hard, greyish-orange, slightly weathered granite.

11 17 Hard, black & white, fresh, equigranular, quartz-plagioclase-pyroxene-biotite granite.

17 21 Hard, orange black & white, slightly weathered, equigranular-quartz-plagioclase-pyroxene-biotite granite.

21 50 Hard, black & white, fresh, equigranular-quartz-plagioclase-pyroxene-biotite granite, with minor moderately weathered bands.

GRANITE


From depth (m)

To depth (m)


0 1 Stiff, pinkish orange, gravelly clayey silt, (possibly transported) SILT

1 3 Stiff, orange, slightly gravelly clayey silt, (extremely weathered granite)

SILT

3 4 Stiff, orange, extremely weathered granite.

4 26 Firm, orange, highly weathered granite.

26 32 Weakly cemented orange-brown, moderately weathered granite.

32 51 Hard, black & white, slightly weathered to fresh quartz-plagioclase-pyroxene-biotite granite., contains fractured and weathered zones.

GRANITE




From depth (m)

To depth (m)


0 3 Stiff, light greyish orange, clayey silt (alluvial?) SILT

3 10 Firm, light orange, extremely weathered granite.

10 16 Firm, light orange, highly weathered, micaceous granite.

16 21 Stiff to weakly cemented, orange, moderately weathered, micaceous granite.

21 28 Stiff, to moderately cemented, orange black and white, slightly weathered, micaceous granite.

28 28 EOH = 28m (due to very soft cohesionless saturated material higher in hole causing it to collapse).

GRANITE


From depth (m)

To depth (m)


0 1 Stiff, very pale brown, fine gravelly sandy silt (alluvium)

1 4 Firm, light orange, finely micaceous, fine sandy silt (alluvium?)

SILT

4 7 Soft, light orange, extremely weathered, micaceous granite.

7 20.5 Firm, light orange, highly weathered, micaceous (biotite) granite.

20.5 24 Very loose, light grey & cream, highly weathered biotite granite.

24 40 Stiff, light grey & cream, highly weathered, biotite granite.

GRANITE


From depth (m)

To depth (m)

Description (Driller’s log) Rock type

0 3 Weathered clay. CLAY

3 24 Decomposed granite.

24 120 Granite.

GRANITE


From depth (m)

To depth (m)


0 3 Clay. CLAY


18 96 Granite.

GRANITE


From depth (m)

To depth (m)


0 4 Red clay. CLAY


24 120 Granite.

GRANITE





From depth (m)

To depth (m)


0 3 Clay. CLAY

3 120 Granite. GRANITE


From depth (m)

To depth (m)


0 6 Clay. CLAY


18 74 Granite.

GRANITE


From depth (m)

To depth (m)


0 3 Sandy clay. CLAY


42 120 Granite.

GRANITE


Appendix B: Hydrographs for bores GW090075, GW090081, GW090082 and GW403607 Hydrograph for monitoring site GW090075 (10 km west of Young)

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Hydrograph for monitoring site GW090082

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Hydrograph for monitoring site GW403607 (Kingsvale)

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Appendix C: Groundwater chemistry data

Bore No. Comments Date

sampled Field EC (S/cm)

Field Eh (mV)

DO (mg/L)

Field pH

Al (mg/L)

As (g/L)

Ba (mg/L)

HCO3 (mg/L)

B (mg/L)

Br (mg/L)

Ca (mg/L)

CO3 (mg/L)

Cl (mg/L)

GW90075 15/11/2005 649 13.2 2.25 6.57 8.2 2 0.36 230 < 0.1 0.5 1 3.4 68

GW90077_1 16/11/2005 466 42.3 3.2 6.07 3.6 <1 0.12 100 < 0.1 0.3 11 < 1 85

GW90077_2 16/11/2005 815 -0.5 1.15 6.82 < 0.05 1 0.059 310 < 0.1 0.4 55 < 1 110

GW90077_2 duplicate 16/11/2005 815 -0.5 1.15 6.82 < 0.05 1 0.12 310 < 0.1 0.4 56 < 1 110

GW90080_2 17/11/2005 1933 2.4 0.27 6.77 0.12 <1 0.14 450 < 0.1 1.3 97 3.1 400

GW90081_1 14/11/2005 2630 -24.4 0.38 7.25 0.15 2 0.45 430 < 0.1 3.5 87 8.4 620

GW90081_2 14/11/2005 3160 3.2 1.36 6.76 0.09 2 0.36 500 < 0.1 3.9 230 < 1 770

GW90082_1 14/11/2005 740 -37 2.52 7.4 0.7 2 0.33 440 0.1 < 0.2 53 23 14

GW90082_2 14/11/2005 590 43.2 0.84 6.06 < 0.05 <1 0.096 170 < 0.1 0.5 49 < 1 93

Bore No. Comments Cu

(mg/L) Fe

(mg/L) Pb

(g/L) Mg

(mg/L) Mn

(mg/L) Hg

(g/L) NO3

(mg/L) NO2

(mg/L) PO4

(mg/L) K

(mg/L) Na

(mg/L) SO4

(mg/L) Zn

(mg/L) SiO2

(mg/L)

GW90075 < 0.02 0 13 1.5 0.16 <0.1 9.1 <0.6 <0.6 0.79 160 38 0.28 58

GW90077_1 < 0.02 3.4 2 14 0.05 <0.1 3.8 <0.6 <0.6 4.7 59 14 0.04 30

GW90077_2 < 0.02 0.31 <1 23 0.44 <0.1 <0.8 <0.6 <0.6 4.6 81 14 < 0.02 40

GW90077_2 duplicate < 0.02 0.3 <1 23 0.45 <0.1 <0.8 <0.6 <0.6 4.7 82 14 0.02 40

GW90080_2 < 0.02 0.07 <1 100 < 0.02 <0.1 36 <0.6 <0.6 5.7 160 42 0.03 26

GW90081_1 < 0.02 0.11 <1 50 0.82 <0.1 2.8 <0.6 <0.6 1.5 390 39 0.04 66

GW90081_2 < 0.02 1.3 <1 140 0.45 <0.1 16 <0.6 <0.6 14 220 75 0.09 39

GW90082_1 < 0.02 0.57 <1 27 0.14 <0.1 <0.8 <0.6 <0.6 1 93 9 0.1 42

GW90082_2 < 0.02 < 0.05 <1 22 < 0.02 <0.1 <0.8 <0.6 <0.6 4.1 34 15 0.1 78

GW90084_2 < 0.02 < 0.05 <1 36 < 0.02 <0.1 2 <0.6 <0.6 1.7 100 26 < 0.02 63


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