Assessment of Basin Plan water quality targets in New South Wales · 2018. 4. 13. · Publisher:...

Assessment of Murray-Darling Basin Plan water quality targets in New South Wales

2007 to 2012

Publisher: NSW Department of Primary Industries, Water

Assessment of Murray-Darling Basin Plan water quality targets in New South Wales; 2007 to 2012

First published November 2015

ISBN 978-1-74256-792-1

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Citation; Mawhinney, W. and Muschal, M. 2015. Assessment of Murray-Darling Basin Plan water quality targets in

New South Wales; 2007 to 2012. New South Wales Department of Primary Industries, Water, Sydney. ISBN 978-1-

74256-792-1

Enquires; Monika Muschal, Team Leader Water Quality, New South Wales Department of Primary Industries, Water.

[email protected]

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Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (December 2015). However,

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Assessment of Basin Plan water quality targets in New South Wales

1 NSW DPI Water, December 2015

Executive summary

The Basin Plan provides a framework for the integrated management of the water resources of

the Murray-Darling Basin. This framework includes the development of water quality

management plans to identify water quality objectives and targets, key causes of water quality

degradation and measures to address these risks.

The objectives of this report are to:

undertake a preliminary assessment of the Basin Plan water quality targets in NSW using

state-wide water quality data collected between July 2007 and June 2012;

compare the differences between the existing national water quality guidelines for the

protection of aquatic ecosystems (the ANZECC Guidelines 2000) and the Basin Plan

water quality targets;

inform the appropriateness of current water quality monitoring and reporting programs to

meet future Basin Plan reporting requirements, and

discuss water quality characteristics in NSW using the Basin Plan water quality targets.

The Basin Plan does not clearly articulate how data should be interpreted or at what scale

reported, only that annual medians should be used and the appropriate application zone water

quality target applied. This report presents options for data interpretation including summary

statistics, annual medians and water quality ratings. Presentation options include a range of

geographical scales; site, application zone and an alternate scale of the larger application zones

divided into catchments. A simple integration of numerous water quality parameters into a single

water quality indicator score has also been trialled and presented at application zone and

catchment scales.

Water quality application zone boundaries were reviewed and one major change recommended;

a change to the Central Murray River zone boundary so that the Edward - Wakool Rivers and

Billabong Creek are separated from the Murray River. The Edward - Wakool Rivers and

Billabong Creek are more alike to the Central Murrumbidgee River in nature than the Central

Murray River and as such the water quality targets for the Murrumbidgee River are more

appropriate.

When the Basin Plan water quality targets were developed, there was insufficient reference data

available to develop water quality targets for the middle and lower zones of the Darling River,

therefore the default trigger values of the national water quality guidelines (ANZECC and

ARMCANZ 2000) were used as the Basin Plan water quality targets. This has resulted in the

illogical scenario of water quality targets in the lower reaches of the Darling being more stringent

than the upstream reaches. The Basin Plan water quality targets for the zone immediately

upstream of the middle and lower Darling zone should be applied across the whole Darling River

until more appropriate water quality targets are developed.

Some monitoring sites have been identified that will exceed the water quality target every year

due to specific catchment conditions (e.g. basaltic geologies, land use). For these areas, local

site specific targets should be developed, as outlined in the Basin Plan.

The Basin Plan water quality targets appear to be more suitable for low flow conditions. The five

year period of data record used in this report spans two different climatic conditions, with drought

conditions breaking to wetter conditions in 2010. This report shows that attributes with a strong

flow relationship are more likely to exceed the water quality targets in wetter years and the flow

conditions of the sampling period must be investigated as part of any future assessment.

Analysis of data from ephemeral streams may result in false reporting during high flows.



The following modifications to the New South Wales water quality monitoring program are

recommended;

additional monitoring sites in upland and montane zones and the Lower Murray zone to

improve the spatial coverage of current monitoring activities;

continued collection of field turbidity and dissolved oxygen data as part of water quality

monitoring programs, and

continued use of continuous dissolved oxygen data in southern lowland rivers and

continuous electrical conductivity data across all inland rivers to give a better assessment

of these parameters than monthly grab samples.



Contents

Executive summary ..................................................................................................................... 1

Contents ..................................................................................................................................... 3

List of Tables ........................................................................................................................... 4

List of Figures .......................................................................................................................... 5

Introduction ................................................................................................................................. 6

Basin Plan water quality zones ................................................................................................ 6

Basin Plan water quality targets ............................................................................................... 9

Assessment method .................................................................................................................. 11

Site selection and data collection ........................................................................................... 11

Site scale water quality ratings .............................................................................................. 11

Zone scale water quality ratings ............................................................................................ 12

Integrated water quality index ................................................................................................ 12

Alternate assessment units .................................................................................................... 12

Electrical conductivity ............................................................................................................ 12

Flow conditions ...................................................................................................................... 13

Results ...................................................................................................................................... 14

Site scale statistics and water quality ratings ......................................................................... 14

Zone scale water quality ratings ............................................................................................ 14

Integrated water quality index ................................................................................................ 21

Alternate assessment units and targets ................................................................................. 23

National water quality guidelines ........................................................................................... 25

Electrical Conductivity ........................................................................................................... 26

Flow Conditions ..................................................................................................................... 27

Discussion ................................................................................................................................ 32

Assessment of Basin Plan water quality targets .................................................................... 32

National water quality guidelines for the protection of aquatic ecosystems ............................ 34

Appropriateness of current monitoring and reporting programs ............................................. 34

State-wide summary of water quality characteristics .............................................................. 35

Conclusions .............................................................................................................................. 39

Recommendations .................................................................................................................... 39

References ............................................................................................................................... 41

Appendix 1 – Water quality monitoring station list ..................................................................... 42

Appendix 2 – Water quality annual median results by site ......................................................... 44

Appendix 3 – Water quality ratings by site ................................................................................. 56

Appendix 4 – Water quality annual medians by zone ................................................................ 58

Appendix 5 – Integrated water quality index rating by site ......................................................... 60

Appendix 6 – Water quality annual medians by catchment within zones ................................... 62

Appendix 7 – Summary statistics .............................................................................................. 65



List of Tables

Table 1 Basin Plan water quality zones ....................................................................................... 7

Table 2 Other water dependent ecosystems target values for Basin Plan water quality zones in

NSW ........................................................................................................................................... 9

Table 3 Basin Salinity Management Strategy – End-of-Valley salinity targets (Water Act 2007) 10

Table 4 Rules for assigning water quality ratings ...................................................................... 11

Table 5 List of selected gauging stations for each water quality zone ....................................... 13

Table 6 Water quality rating for each parameter and application zone ...................................... 14

Table 7 Water quality rating of integrated water quality index in each water quality zone .......... 21

Table 8 Water quality rating for each alternative zone-catchment assessment unit ................... 23

Table 9 Comparison of Basin Plan water quality targets against the ANZECC Guidelines (2000)

default trigger values for turbidity, total phosphorus and total nitrogen ...................................... 25

Table 10 Assessment of annual median electrical conductivity (µS/cm at 25°C) data against

End-of-Valley salinity targets (Water Act 2007) ......................................................................... 26

Table 11 List of NSW monitoring stations .................................................................................. 42

Table 12 Annual median laboratory turbidity (NTU) 2007-2012 ................................................. 44

Table 13 Annual median field turbidity (NTU) 2007-2012 .......................................................... 46

Table 14 Annual median total phosphorus (µg/L) 2007-2012 .................................................... 48

Table 15 Annual median total nitrogen (µg/L) 2007-2012 .......................................................... 50

Table 16 Annual median field pH 2007-2012............................................................................. 52

Table 17 Annual median dissolved oxygen (% saturation) 2007-2012 ...................................... 54

Table 18 Water quality index ratings by site for each parameter ............................................... 56

Table 19 Annual medians of data for all sites in each water quality zone .................................. 58

Table 20 Integrated water quality rating by site ......................................................................... 60

Table 21 Annual medians of all sites in major catchments in each water quality zone ............... 62



List of Figures

Figure 1 Location of NSW monitoring stations and Basin Plan water quality zones ..................... 8

Figure 2 Assessment of laboratory turbidity results against Basin Plan targets ......................... 15

Figure 3 Assessment of field turbidity against Basin Plan targets .............................................. 16

Figure 4 Assessment of total phosphorus against Basin Plan targets ....................................... 17

Figure 5 Assessment of total nitrogen against Basin Plan targets ............................................. 18

Figure 6 Assessment of field pH against Basin Plan targets ...................................................... 19

Figure 7 Assessment of dissolved oxygen against Basin Plan targets....................................... 20

Figure 8 Rating of integrated water quality index based on Basin Plan targets .......................... 22

Figure 9 Water quality ratings for alternative zone-catchment assessment units ....................... 24

Figure 10 Flow at selected gauging stations in the Condamine, Paroo and Warrego (lowland)

water quality zone ..................................................................................................................... 27

Figure 11 Flow at selected gauging stations in the Border Rivers, Gwydir and Namoi (lowland)


Figure 12 Flow at selected gauging stations in the Castlereagh, Lachlan, Macquarie and

Murrumbidgee (lowland) water quality zone .............................................................................. 28

Figure 13 Flow at selected gauging stations in the Border Rivers, Gwydir and Namoi (upland)


Figure 14 Flow at selected gauging stations in the Castlereagh, Lachlan, Macquarie and

Murrumbidgee (upland) water quality zone ............................................................................... 28

Figure 15 Flow at selected gauging stations in the Kiewa, Mitta Mitta and Upper Murray (upland)


Figure 16 Flow at selected gauging stations in the Border Rivers, Gwydir and Namoi (montane)


Figure 17 Flow at a selected gauging station in the Lachlan and Murrumbidgee (montane) water

quality zone ............................................................................................................................... 29

Figure 18 Flow at selected gauging stations in the Central Murray (upper and middle) water

quality zone ............................................................................................................................... 30

Figure 19 Flow at a selected gauging station in the Central Murray (lower) water quality zone . 30

Figure 20 Flow at selected gauging stations in the Darling (upper) water quality zone .............. 30

Figure 21 Flow at selected gauging stations in the Darling (middle and lower) water quality zone

.................................................................................................................................................. 31



Introduction

The Basin Plan 2012 is an instrument of the Commonwealth Water Act (2007) and provides the

framework for the long term integrated management of the water resources of the Murray-

Darling Basin (the Basin).

The Basin Plan requires the development of water quality management plans for all water

resources in the Basin. Each plan will;

establish water quality objectives and targets for freshwater dependent ecosystems, irrigation water and recreational purposes;

identify key causes of water quality degradation;

assess risks arising from water quality degradation, and

identify measures that contribute to achieving water quality objectives.

This report provides an assessment of the Basin Plan water quality targets (the targets) for fresh

water-dependent ecosystems in New South Wales (NSW). The targets set out the appropriate

water quality required for environmental, social, cultural and economic benefits in the Basin.

Monitoring progress towards achieving the targets will identify trends and inform actions that

address the causes of water quality decline. The Basin Plan allows for alternative water quality

targets to be specified following the procedures in the National Water Quality Management

Strategy (the ANZECC Guidelines 2000), (ANZECC and ARMCANZ 2000). The focus of this

report is on physical and chemical stressors, not toxicants, in NSW rivers.

The Basin Plan requires reporting of progress towards the water quality targets every five years.

Therefore, this assessment provides a five year review of water quality data from 1 July 2007 to

30 June 2012.

The objectives of this report are to:

undertake a preliminary assessment of the Basin Plan water quality targets in NSW using

state-wide water quality data collected between July 2007 and June 2012;

compare the differences between the existing national water quality guidelines for the

protection of aquatic ecosystems (the ANZECC Guidelines 2000) and the Basin Plan

water quality targets;

inform the appropriateness of current water quality monitoring and reporting programs to

meet future Basin Plan reporting requirements, and

discuss water quality characteristics in NSW using the Basin Plan water quality targets.

It is outside the scope of this report to undertake a full evaluation of current water quality

monitoring programs. It is also not the intention of this report to investigate the compatibility of

reporting procedures of neighbouring jurisdictions: Queensland, Victoria, South Australia and the

Australian Capital Territory.

Basin Plan water quality zones

The Basin Plan sets out water quality “target application zones”, approximating lowland, upland

and montane areas of major river valleys. Lowland areas have an altitude of less than 200

metres, upland areas fall between 200 and 700 metres and montane areas have an altitude

greater than 700 metres. Zone descriptors and the number of NSW water quality monitoring

stations located within each zone are listed in Table 1. Of the 21 zones across the Murray-

Darling Basin, 14 fall wholly or partially within NSW. There is no data available for two zones

(Lower Murray (lM) and Mitta Mitta and Upper Murray montane (C6) zones) and they are not



included in this assessment. The locations of water quality monitoring sites are shown in Figure

1. A full list of sites is given in Appendix 1.

Table 1 Basin Plan water quality zones

Basin Plan Water

Quality Zone

Valley Number of water quality monitoring stations in NSW

A1 Condamine, Paroo, Warrego (lowland) 6

A2 Border Rivers, Gwydir, Namoi (lowland) 8

A3 Castlereagh, Lachlan, Macquarie, Murrumbidgee (lowland)

18

A4* Avoca, Campaspe, Loddon and Wimmera (lowland) N/A

A5* Broken, Goulburn and Ovens (lowland) N/A

A6* Kiewa (lowland) N/A

B1* Condamine and Warrego (upland) N/A

B2 Border Rivers, Gwydir and Namoi (upland) 30

B3 Castlereagh, Lachlan, Macquarie and Murrumbidgee (upland)

27

B4* Avoca, Campaspe, Loddon and Wimmera (upland) N/A

B5* Broken, Goulburn and Ovens (upland) N/A

B6 Kiewa, Mitta Mitta and Upper Murray (upland) 3

C2 Border Rivers, Gwydir and Namoi (montane) 3

C3 Lachlan and Murrumbidgee (montane) 1

C5* Ovens (montane) N/A

C6 Mitta Mitta and Upper Murray (montane) 0

cMl Central Murray (lower) 2

cMum Central Murray (upper, middle) 9

Du Darling (upper) 3

Dml Darling (middle, lower) 5

IM Lower Murray (lower) 0

* Indicates zones not within NSW



Figure 1 Location of NSW monitoring stations and Basin Plan water quality zones



Basin Plan water quality targets

The Basin Plan water-dependent ecosystem targets for turbidity, total phosphorus, total nitrogen,

dissolved oxygen and pH were developed following the methods outlined in the ANZECC

Guidelines (2000). Water quality data for rivers and streams in ‘reference’ condition from each of

the water quality zones were used to develop the target values for each zone (Tiller and Newall

2010). Where there were no reference sites, the appropriate default trigger value from the

ANZECC Guidelines (2000) for slightly to moderately disturbed systems was used as the Basin

Plan water quality target (Tiller and Newall 2010).

For each zone, a high, moderate or low confidence was assigned to the water quality targets

(Tiller and Newall 2010). The zones with low confidence include:

Border Rivers, Gwydir, Namoi (montane) (C2)

Lachlan, Murrumbidgee (montane) (C3)

Darling Main Stem (upper) (Du)

Darling Main Stem (middle) (Dm)

Darling Main Stem (lower) (Dl)

Murray Valley (lower) (lM)

Two water-dependent ecosystems are described in the Basin Plan; Declared Ramsar wetlands

(streams and rivers; lakes and wetlands) and Other water-dependent ecosystems (streams,

rivers, lakes and wetlands). The water quality targets assessed in this report are for Other water-

dependent ecosystems, as listed in Table 2.

Table 2 Other water dependent ecosystems target values for Basin Plan water quality zones in NSW

Basin Plan WQ Zone

Turbidity (NTU)

Total Phosphorus (µg/L)

Total Nitrogen (µg/L)

Dissolved Oxygen (%sat)

pH

A1 700 300 1000 60 – 110 6.5 – 8.0

A2 200 200 1000 65 - 110 7.0 – 8.3

A3 35 50 600 80 - 110 6.5 – 8.0

B2 30 80 750 60 - 110 7.5 - 8.5

B3 20 35 600 90 - 110 7.0 – 8.0

B6 5 30 350 85 - 110 6.4 – 7.7

C2 25 20 250 90 - 110 6.5 – 7.5

C3 10 20 250 90 - 110 6.5 – 7.5

C6 5 25 150 95 - 110 6.4 – 7.7

cMum 15 40 500 90 - 110 6.5 – 7.5

cMl 35 80 700 90 - 110 6.8 – 8.0

Du 230 250 900 80 - 110 7.0 – 8.1

Dml 50 50 500 85 - 110 6.5 – 8.0

IM 50 100 1000 85 - 110 6.5 – 9.0

The Basin Plan water temperature target is that the monthly median is between the 20th and

80th percentiles of the natural monthly range. The river catchments of the Basin have been

extensively modified from the natural state by river regulation and changes to land use.

Estimating or modelling the natural monthly temperature distribution for each monitoring site is

beyond the scope of this assessment and therefore water temperature targets are not discussed

further.

Electrical conductivity targets are not described for each water quality zone of the Basin Plan.

Instead, the Murray-Darling Basin End-of-Valley salinity targets, as described in Schedule B

Appendix 1 of the Commonwealth Water Act (2007), have been incorporated into the water

quality targets. The NSW End-of-Valley targets are listed in Table 3.



Table 3 Basin Salinity Management Strategy – End-of-Valley salinity targets (Water Act 2007)

Valley Reporting site number

Reporting Site End-of-Valley Targets (absolute value)

Median (50%ile) (µS/cm)

Peak (80%ile) (µS/cm)

Salt load (t/yr)

Murrumbidgee 410130 Murrumbidgee River D/S Balranald Weir

162 258 169 600

Lachlan 412004 Lachlan River at Forbes (Cottons Weir)

460 693 257 500

Bogan 421023 Bogan River at Gongolgon 581 456 34 830

Macquarie 421012 Macquarie River at Carinda (Bells Bridge)

504 744 25 760

Castlereagh 420020 Castlereagh River at Gungalman Bridge

368 - 8 910

Namoi 419026 Namoi River at Goangra 475 715 127 600

Gwydir 418058 Mehi River at Bronte 412 545 7 000

NSW Border Rivers

416001 Macintyre River at Mungindi 250 330 50 000

Barwon Darling

425008 Darling River at Wilcannia Main Channel

389 453 576 400

Condamine Balonne

422015 Culgoa River at Brenda 170 210 29 000

Condamine Balonne

422030 Narran River at New Angledool 160 210 10 000

Warrego 423004 Warrego River at Barringun No.2 101 110 4 800

Warrego 423005 Cuttaburra Creek at Turra 100 130 5 500



Assessment method

Site selection and data collection

The water quality data used in this report were compiled from 115 water quality monitoring

stations located within the Murray-Darling Basin and routinely monitored by DPI Water. The

majority of the data (87 sites) were collected via the State Water Quality Assessment and

Monitoring Program. This water quality monitoring program is responsible for collecting,

analysing and reporting the ambient water quality condition of rivers in NSW. The program in its

current form commenced in November 2007 to replace numerous regionally based water quality

monitoring programs. An additional 21 sites were monitored in the NSW Border Rivers and

Intersecting Streams for the Dumaresq-Barwon Border Rivers Commission and seven sites were

monitored in the Lower Murray-Darling region for the Murray-Darling Basin Authority. A full

station list is given in Appendix 1.

Data collection involves a team of regionally based staff located across NSW who visit fixed river

sampling stations to record in-situ water quality conditions using portable instruments and collect

water samples that are preserved and sent for analysis at the DPI Water laboratory. Most

sampling was undertaken monthly with the exception of some sites in the Lower Murray-Darling

which were sampled weekly. For the purposes of this report one monthly reading was selected

from the weekly monitored data record for consistency across the data set.

Quality control procedures consistent with Australian Standards for Water Quality Sampling

(AS/NZS 5667.1:1998 and AS/NZS 5667.6:1998) were applied to all programs. Laboratory

analysis was undertaken at the DPI Water’s NATA accredited laboratory. All field and laboratory

data were audited, validated and archived in the corporate water quality database, the Kisters

Water Quality Module (KiWQM).

Site scale water quality ratings

Summary statistics (minimum, 20th percentile, 25th percentile, median, 75th percentile, 80th

percentile and maximum) for all sites have been calculated and are available as a separate

electronic file.

Medians for each site have been calculated on an annual record from 1 July to 30 June for the

five years 2007 to 2012. This report includes the water quality parameters of turbidity (field and

laboratory results), total nitrogen, total phosphorus, dissolved oxygen and pH (field results). Field

turbidity results are preferred to laboratory results, however due to the lack of field data in the

early record for some areas, both field and laboratory results have been presented in this report.

Annual medians for each site have been compared to the Other water dependent ecosystems

(streams, rivers and wetlands) target values for the appropriate water quality zone.

Annual median results have been integrated to give a single rating for the entire five year data

record. Each site and water quality parameter was scored ‘1’ if the annual median was less than

the target and ‘0’ if it exceeded the target. An average annual score was then calculated for each

site and parameter to represent the exceedance of the target for the period 2007 to 2012. A

classification scheme was then created to rank the overall exceedance into a five-step scale

from Very Poor to Very Good (Table 4).

Table 4 Rules for assigning water quality ratings

Water Quality Rating Classification score

Very Good 0.81 - 1

Good 0.61- 0.8

Moderate 0.41 - 0.6

Poor 0.21 - 0.4

Very poor 0 - 0.2



The number of data points used to calculate a median can influence the statistic and confidence

in the result. An acceptable sampling effort should be met for a result to be considered a

genuine representation of typical water quality conditions. In this report, the judgement was

made that five samples collected in a year (not taking into account the distribution of samples

throughout the year) was the minimum sample size required to achieve a reasonable confidence

in the interpretation of the results. The majority of sites had 10 to 12 samples collected annually.

Sites with less than five samples were still assigned a rating but identified as having an

incomplete data set.

Zone scale water quality ratings

Data for all sites in each target application zone was aggregated into a single dataset and an

annual median calculated per parameter. Water quality ratings were applied to the zone

medians using the same scoring method and classification scheme as set out in Table 4.

Integrated water quality index

Following the assessment of individual water quality parameters, an integrated water quality

index was developed that includes turbidity, total nitrogen, total phosphorus, dissolved oxygen

and pH. Using a standard Euclidean Distance formula, individual parameters were combined

into a single overall water quality index for each site, both the site and zone scale ratings. No

weighting of parameters or expert rules have been applied. The formula is:

WQ index = 1 - √ ((1 - A)2 + (1 - B)2 + (1 – C)2 + (1 – D)2 + (1 – E)2) / √ N

where A, B, C, D and E are individual parameter scores for the full five year period and the

denominator is the square root of the total number of parameter scores N. The water quality

index is then assigned a water quality rating using the same classification scheme as set out in

Table 4. The standard Euclidean distance approach is recommended by the Framework for the

Assessment of River and Wetland Health (FARWH). It deals with different scales of

measurement for various parameters and large inter-sample differences, in multi-dimensional

space.

Alternate assessment units

Results for large water quality application zones that include several catchments, such as the

Castlereagh, Macquarie, Lachlan, Murrumbidgee upland zone (B3) can be presented using

alternate boundaries based on catchments within the larger zones. The 12 Basin Plan

application zones in NSW have been separated into 23 zone-catchment assessment units. Site

results have been re-aggregated to calculate both individual parameter and integrated water

quality index results for these alternate zone-catchment scale units.

Electrical conductivity

The annual median of the reporting site has been compared to the appropriate End-of-Valley

target. Some application zones contain multiple End-of-Valley targets, so the assessment has

been done by catchment rather than by zone. For example, the Border Rivers, Gwydir, Namoi

lowland zone (A2) contains three different median electrical conductivity targets; the Namoi

River at Goangra (475 µS/cm), Mehi River at Bronte (412 µS/cm) and Macintyre River at

Mungindi (250 µS/cm).



Flow conditions

During the 2007 to 2012 data period, many parts of NSW experienced the end of prolonged

drought conditions. Significant changes to river flows are likely to be reflected in water quality.

Total annual flow for the reporting period is presented for selected sites within each water quality

zone to demonstrate the variability. Where possible, several sites were selected to represent

flow conditions across each zone. Table 5 lists the gauging stations used in each zone.

Table 5 List of selected gauging stations for each water quality zone

WQ Zone Station Number Station Name

A1 422030 Narran River at New Angledool

A1 422015 Culgoa River at Brenda

A1 424002 Paroo River at Willara Crossing

A2 416001 Barwon River at Mungindi

A2 418058 Mehi River at Bronte

A2 419026 Namoi River at Goangra

A3 410040 Murrumbidgee River D/S Maude Weir

A3 412005 Lachlan River at Booligal

A3 421012 Macquarie River at Carinda (Bells Bridge)

A3 421023 Bogal River at Gongolgan

B2 416012 Macintyre River at Holdfast (Yelarbon Crossing)

B2 416040 Dumaresq River at Glenarbon Weir

B2 418013 Gwydir River at Gravesend

B2 419001 Namoi River at Gunnedah

B3 410004 Murrumbidgee River at Gundagai

B3 412004 Lachlan River at Forbes (Cottons Weir)

B3 421001 Macquarie River at Dubbo

B6 401014 Tooma River at Pinegrove

B6 401549 Murray River at Bringenbong

C2 416039 Severn River at Strathbogie

C2 418014 Gwydir River at Yarrowyck

C2 419010 Macdonald River at Woolbrook

C3 410033 Murrumbidgee River at Mittagang Crossing

cMum 409003 Edward River at Deniliquin

cMum 409005 Murray River at Barham

cMum 409025 Murray River D/S Yarrawonga Weir

cMum 410016 Billabong Creek at Jerilderie

cMl 425010 Murray River at Lock 10 Wentworth

Du 422001 Barwon River at Dangar Bridge (Walgett)

Du 422002 Barwon River at Brewarrina

Du 422003 Barwon River at Collarenebri

Dml 425003 Darling River at Bourke Town

Dml 425008 Darling River at Wilcannia Main Channel

Dml 425012 Darling River U/S Weir 32



Results

Site scale statistics and water quality ratings

The annual median of each parameter at each monitoring site has been compared to the

relevant Basin Plan water quality target. The annual median and the number of samples

collected per year for each parameter are displayed in Appendix 2.

A water quality rating for each site has been calculated based on the number of years (annual

median) the target for that indicator was exceeded between 2007 and 2012. Figures 2 to 7

illustrate the site ratings for each parameter. The water quality ratings for each site and

parameter are shown in Appendix 3.

Zone scale water quality ratings

Data for all sites located within each water quality application zone have been aggregated and

the annual median for each parameter calculated. All annual medians per zone are compared to

the appropriate target and displayed in Appendix 4. A water quality rating was calculated based

on the number of years the target for that indicator, per zone, was exceeded between 2007 and

2012. Table 6 summarises the parameter ratings for each zone, with Very Poor classifications

highlighted. Figures 2 to 7 illustrate the zone ratings for each parameter.

Table 6 Water quality rating for each parameter and application zone

WQ Zone Turbidity

(Lab) Turbidity

(Field) Total P Total N

Dissolved Oxygen

pH

A1 Very Good Poor Very Good Moderate ID Very Good

A2 Very Good Good Very Good Very Good ID Very Good

A3 Moderate Moderate Moderate Moderate Very Good Very Good

B2 Very Good Good Very Good Good ID Very Good

B3 Very Good Very Good Poor Good Very Good Very Good

B6 Poor Very Poor Very Good Very Good Very Good Very Good

C2 Very Good Good Very Poor Very Poor ID Very Poor

C3 Very Good Very Good Moderate Good Very Good Very Good

cMum Very Poor Very Poor Moderate Moderate Good Very Good

cMl Good Good Good Good Good Very Good

Du Very Good Very Good Very Good Good ID Very Good

Dml Very Poor Very Poor Very Poor Very Poor Moderate Good

ID – Insufficient data to apply a rating

The turbidity, total phosphorus and total nitrogen annual medians exceeded the Basin Plan

water quality targets for the Darling - middle, lower zone (Dml) in all five years resulting in water

quality ratings of Very Poor. Other zones with Very Poor ratings are turbidity (laboratory and

field) in the Central Murray zone (cMum), field turbidity in the Kiewa, Mita Mitta, Upper Murray

uplands zone (B6) and total nitrogen, total phosphorus and pH in the Border Rivers, Gwydir,

Namoi montane zone (C2).



Turbidity – laboratory data

Most sites in the Central Murray (cMum) and the Darling - middle, lower (Dml) zones were rated

as Very Poor. The majority of sites in other zones were rated as Good to Very Good with the

occasional Very Poor at sites with high turbidity. The high turbidity at these sites is largely

attributed to local catchment conditions such as land use or soil type. There was an increase in

the number of sites that exceeded the turbidity targets in 2010/2011 and 2011/2012, most likely

due to higher flows. The zone results show the montane, the majority of upland zones and the

Intersecting Streams all rated as Very Good. The high number of Very Poor sites in the Central

Murray and Darling - middle, lower zones resulted in zone ratings of Very Poor.

Figure 2 Assessment of laboratory turbidity results against Basin Plan targets



Turbidity – field data

There were numerous sites with insufficient field turbidity data to assign a site rating. The

majority of these sites are located in the north of the Basin. Similar to the laboratory data, there

were a high number of sites rated as Very Poor in the Central Murray (cMum) and Darling -

middle, lower (Dml) zones and the occasional Very Poor in other zones at sites with high

turbidity due to local catchment conditions. The combination of site data within each water

quality zone provided sufficient data to apply a zone rating. As for the laboratory turbidity data,

the Central Murray (cMum) and Darling - middle, lower zones were rated as Very Poor. There

were fewer zones rated as Very Good using the field data compared to the laboratory turbidity

data.

Figure 3 Assessment of field turbidity against Basin Plan targets



Total Phosphorus

There were numerous sites in the Darling - middle, lower zone (Dml) exceeding the total

phosphorus target every year. There is a cluster of sites in the Murrumbidgee catchment located

upstream of Wagga Wagga (zone B3) and three sites in the Namoi catchment (zone B2) rated

as Very Poor. Many other sites did not exceed the targets in the low flow years of 2007 to 2010,

but did exceed the targets in the high flow years between 2010 and 2012, giving them a rating of

Moderate or Good. The combination of data in the Border Rivers, Gwydir and Namoi montane

(C2) and Darling - middle, lower (Dml) zones resulted in a Very Poor rating for these zones. In

other zones (e.g. Border Rivers, Gwydir, Namoi uplands zone (B2)) the high total phosphorus

results from some sites have been averaged out by low results from other catchments, resulting

in a Very Good rating.

Figure 4 Assessment of total phosphorus against Basin Plan targets



Total Nitrogen

Nitrogen and phosphorus have a similar mode of transport through a river system, however the

results from the two nutrients were not exactly the same. The Darling - middle, lower (Dml) and

Border Rivers, Gwydir and Namoi montane (C2) zones have sites exceeding the Basin Plan

targets and rated as Very Poor. Other sites rated as Very Poor were not isolated to particular

zones but dispersed across the state. As with previous parameters there is a strong flow

relationship, with site exceedances increasing during 2010 to 2012. The Border Rivers, Gwydir

and Namoi lowland (A2) and the Upper Murray (B6) were the only zones to be rated as Very

Good. As for total phosphorus, the Border Rivers, Gwydir and Namoi montane (C2) and Darling

- middle, lower (Dml) zones rated as Very Poor.

Figure 5 Assessment of total nitrogen against Basin Plan targets



pH

The Severn River at Strathbogie Bridge and Gwydir River at Yarrowyck, both in the Border

Rivers, Gwydir and Namoi montane zone (C2), were rated as Very Poor. The high pH at these

sites resulted in a Very Poor rating for this zone. Most sites were rated as Good or Very Good

and this is reflected in the zone rating for most of the state.

Figure 6 Assessment of field pH against Basin Plan targets



Dissolved Oxygen

There were a high proportion of sites with insufficient data in the north of the Basin, making

assessment of the dissolved oxygen targets difficult for this assessment period. Sites on the

lower Lachlan River (zone A3) and Billabong Creek in the Central Murray zone (cMum) were

rated as Poor. The combination of data did not resolve the issue of insufficient data in the

northern zones. Zones in central NSW were rated as Very Good, with the Central Murray being

Good, and Darling - middle, lower zone (Dml) rated as Moderate.

Figure 7 Assessment of dissolved oxygen against Basin Plan targets



Integrated water quality index

An integrated water quality index was developed that combines turbidity, total nitrogen, total

phosphorus and pH scores using a standard Euclidean Distance formula. As many zones have

insufficient dissolved oxygen data, it has been excluded from calculating the index. Dissolved

oxygen will be included in future assessments. Due to the incomplete field turbidity data set,

laboratory turbidity ratings have been used. In future assessments, field turbidity will be used as

it is more indicative of in-situ conditions.

The water quality index has been calculated at both the site scale and the zone scale. No

weighting of individual parameters was applied. The index was given an overall water quality

rating using the same classification scheme for individual parameters, as described in Table 4.

The results of the integrated rating by site are shown in Appendix 5, and the zone rating in Table

7. Figure 8 displays the integrated rating at both the site and zone scales.

Table 7 Water quality rating of integrated water quality index in each water quality zone

Zone Rating

A1 – Condamine Paroo Warrego Good

A2 – Border Rivers Gwydir, Namoi (lowland) Very Good

A3 – Castlereagh, Lachlan, Macquarie, Murrumbidgee (lowland) Good

B2 – Border Rivers, Gwydir, Namoi (upper) Very Good

B3 – Castlereagh, Lachlan, Macquarie, Murrumbidgee (upper) Good

B6 – Kiewa, Mitta Mitta, Upper Murray (upper) Good

C2 – Border Rivers, Gwydir, Namoi (montane) Very Poor

C3 – Lachlan, Murrumbidgee (montane) Good

C6 – Mitta Mitta, Upper Murray (montane) No data

cMum – Central Murray (upper, middle) Moderate

cMl – Central Murray (lowland) Very Good

Du – Darling (upper) Very Good

Dml – Darling (middle, lowland) Very Poor

IM – Lower Murray (lowland) No data

The integration of the ratings of all parameters from each zone shows that the majority of zones

are rated as Good. The Border Rivers, Gwydir, Namoi montane zone (C2) rated as Very Poor,

mainly due to high total nitrogen, total phosphorus and pH results. The Darling - middle, lower

zone (Dml) was the only other water quality zone to rate as Very Poor. The Central Murray zone

(cMum) rated as Moderate due to high turbidity.



Figure 8 Rating of integrated water quality index based on Basin Plan targets



Alternate assessment units and targets

For reporting purposes, an alternative to presenting results across large application zones is to

present results at a major catchment scale for each zone. The 12 Basin Plan water quality

application zones within NSW have been broken into 23 zone-catchment assessment units.

Water quality ratings for each zone-catchment unit have been re-calculated, based on the

exceedance of the Basin Plan water quality targets for the period 2007 to 2012 (Table 8). This is

the same method used for the zone scale. The annual medians are displayed in Appendix 6.

In the Central Murray zone (cMum), the smaller river systems of the Edward - Wakool Rivers

and Billabong Creek function as lowland rivers, especially when compared to the Murray River at

Albury and downstream of Yarrawonga Weir. This report has created two new assessment units;

cWEB - Wakool, Edward, Billabong using the water quality targets for zone A3 (Table 8),

cM - central Murray retaining the original water quality targets for zone cMum (Table 8).

The Basin Plan water quality targets for the Darling - middle, lower zone (Dml) were based on

the default trigger values of the ANZECC Guidelines (2000) as there were inadequate

monitoring data available at the time to derive new Basin Plan water quality targets (Tiller and

Newell 2010). However, the targets for the Darling upper zone (Du) were derived using available

monitoring data. This has resulted in the targets for the middle and lower zones of the Darling

(e.g. for turbidity 50 NTU) to be much lower than those of the Darling upper zone (230 NTU) and

Intersecting Streams (700 NTU), which are both immediately upstream. In the following analysis,

the water quality targets for the Darling upper zone (Du) (900 µg/L) have been applied to the

Darling - middle, lower zone (Dml) (Table 8).

Table 8 Water quality rating for each alternative zone-catchment assessment unit

Assessment unit Turbidity

(Lab) Turbidity

(Field) Total P Total N

Dissolved Oxygen

pH Integrated

rating

A1 – Intersecting Streams

Good ID Very Good Good ID Very Good Very Good

A1 – Paroo Moderate ID Very Good Moderate ID Good Good

A1 – Warrego Moderate ID Good Moderate ID Moderate Good

A2 – Border Rivers (L) Very Good Poor Very Good Good ID Very Good Very Good

A2 – Gwydir (L) Very Good Poor Very Good Good ID Very Good Very Good

A2 – Namoi (L) Very Good Very Good Very Good Very Good ID Very Good Very Good

A3 – Macquarie (L) Very Poor Very Poor Very Poor Very Poor ID Good Very Poor

A3 – Lachlan (L) Moderate Very Poor Very Poor Very Poor Moderate Very Good Poor

A3 – Murrumbidgee (L) Moderate Moderate Moderate Good Very Good Very Good Good

B2 – Border Rivers (U) Very Good Good Very Good Good ID Very Good Very Good

B2 – Gwydir (U) Very Good Very Good Very Good Very Good ID Very Good Very Good

B2 – Namoi (U) Very Good Very Good Poor Very Good ID Very Good Good

B3 – Macquarie (U) Very Good Very Good Moderate Good Very Poor Good Good

B3 – Lachlan (U) Moderate Very Good Very Poor Moderate Very Poor Very Poor Poor

B3 – Murrumbidgee (U) Very Good Very Good Poor Very Good Very Good Good Good

B6 – Upper Murray Poor Very Poor Very Good Very Good Very Good Very Good Good

C2 – Border Rivers, Gwydir, Namoi (M)

Very Good Very Good Very Poor Very Poor Very Poor Very Poor Very Poor

C3 – Lachlan, Murrumbidgee (M)

Very Good Very Good Moderate Good Very Good Very Good Good

cWEB – Wakool, Edward, Billabong

Very Poor Very Poor Moderate Moderate Good Very Good Moderate

cM – Murray Central Good Good Good Good Very Good Very Good Very Good

cMl – Murray (middle, lower)

Good Good Good Good Good Very Good Very Good

Du – Darling (upper) Very Good Very Good Very Good Good ID Very Good Very Good

Dml – Darling (middle, lower)

Good Good Moderate Very Poor Good Good Moderate



Figure 9 Water quality ratings for alternative zone-catchment assessment units

A large portion of NSW is still rated as Good using the alternate zone-catchment assessment

units and the alternate targets for the Wakool, Edward, Billabong (cWEB) and Darling - middle,

lower (Dml) zones; but not to the same degree as in Figure 8. The key differences in results

between the integrated water quality rating for the Basin Plan application zones (Figure 8)

versus the alternate zone-catchment units and targets (Figure 9) are:

the upland reaches of the Namoi River decreased from Very Good to Good;

the Macquarie lowlands decreased from Good to Very Poor;

the lower Darling improved from Very Poor to Moderate;

the Intersecting Streams increased from Good to Very Good;



the Lachlan catchment in zones A3 and B3 decreased from Good to Poor, and

the central Murray zone has increased from Moderate to Very Good.

The integrated rating for the alternate zone-catchment unit of the Wakool, Edward, Billabong

(cWEB) is Moderate. By applying the turbidity target of 35 NTU instead of 15 NTU to this new

zone, the two sites on Billabong Creek are still rated as Very Poor, but other sites in the zone

range from Poor to Good. The integrated rating for the central Murray (cM) as a stand-alone

zone has increased to Very Good.

National water quality guidelines

A comparison is made between the default trigger values of the national water quality guidelines

for the protection of aquatic ecosystems (the ANZECC Guidelines 2000) and the Basin Plan

water quality targets for turbidity, total phosphorus and total nitrogen (Table 9).

The largest differences between the two sets of guideline values are in the lowland rivers of the

Condamine, Paroo, Warrego (A1) and the Border Rivers, Gwydir and Namoi (A2) zones. The

Basin Plan targets for these zones were developed from reference data and are considerably

higher than the default trigger values of the ANZECC Guidelines (2000).

The Basin Plan targets for the upper Darling River zone (Du) were also developed using

reference data and are higher than the default trigger values of the ANZECC Guidelines (2000).

All the Basin Plan targets for the Darling - middle, lower zone (Dml) have been taken straight

from the default trigger values of the ANZECC Guidelines (2000) and are therefore the same.

The Basin Plan targets for total phosphorus are the same or slightly higher than the ANZECC

Guidelines (2000) default trigger values for all the upland and montane zones. Basin Plan

targets for total nitrogen are similar to the ANZECC Guidelines (2000) default trigger values in all

montane areas (C2 and C3) with the exception of the Murray montane zone (C6), which is lower.

In all other zones the Basin Plan targets for total nitrogen are higher than the ANZECC

Guidelines (2000) default trigger values.

The Central Murray - upper, middle zone (cMum) has a turbidity target of 15 NTU while the

ANZECC Guidelines (2000) default trigger value is 50 NTU. As indicated previously, it is

recommended that the zone boundaries and targets for this zone be changed. Some turbidity

targets from the upland (B6) and montane (C3 and C6) zones are also much lower than the

ANZECC Guidelines (2000) default trigger values. The lack of monitoring sites in the montane

zones made it difficult to assess these targets with any confidence.

Table 9 Comparison of Basin Plan water quality targets against the ANZECC Guidelines (2000) default trigger values for turbidity, total phosphorus and total nitrogen

Basin Plan WQ Zone

Turbidity (NTU) Total Phosphorus (µg/L) Total Nitrogen (µg/L)

Basin Plan ANZECC* Basin Plan ANZECC* Basin Plan ANZECC*

A1 700 50 300 50 1000 500

A2 200 25/50 200 20/50 1000 250/500

A3 35 25/50 50 20/50 600 250/500

B2 30 25 80 20 750 250

B3 20 25 35 20 600 250

B6 5 25 30 20 350 250

C2 25 25 20 20 250 250

C3 10 25 20 20 250 250

C6 5 25 25 20 150 250

cMum 15 25/50 40 20/50 500 250/500

cMl 35 50 80 50 700 500

Du 230 50 250 50 900 500

Dml 50 50 50 50 500 500

IM 50 50 100 50 1000 500

* Where two ANZECC targets are listed, the first is for upland rivers and the second for lowland rivers



Electrical Conductivity

The Namoi River at Goangra was the only End-of-Valley site to meet both the median and 80th

percentile targets in all five years. Most sites exceeded at least one of the targets in 2011 to

2012 during the period of higher flows. The Narran River at New Angledool exceeded both

targets all five years however the number of samples collected was low. The Culgoa River at

Brenda also exceeded the targets most years.

Table 10 Assessment of annual median electrical conductivity (µS/cm at 25°C) data against End-of-Valley salinity targets (Water Act 2007)

Valley Site number

Reporting Site name End of Valley Targets

2007-2012 data

Median (50%ile)

Peak (80%ile)

Year n Median 80%ile

Murrumbidgee 410130 Murrumbidgee River D/S Balranald Weir

(Data from 41010901

Balranald Weir Storage)

162 258 2007/2008 12 164 248

2008/2009 11 102 124

2009/2010 12 126 153

2010/2011 11 180 246

2011/2012 12 177 213

Lachlan 412004 Lachlan River at Forbes

(Cottons Weir)

460 693 2007/2008 10 355 359

2008/2009 12 391 426

2009/2010 10 444 482

2010/2011 10 671 746

2011/2012 11 611 793

Bogan 421023 Bogan River at Gongolgon 581 456 2007/2008 4 223 280

2008/2009 6 216 276

2009/2010 6 180 189

2010/2011 5 250 428

2011/2012 10 292 862

Macquarie 421012 Macquarie River at Carinda

(Bells Bridge)

504 744 2007/2008 4 582 666

2008/2009 4 484 599

2009/2010 2 466 489

2010/2011 4 473 623

2011/2012 11 560 884

Castlereagh 420020 Castlereagh River at

Gungalman Bridge

368 - No data available

Namoi 419026 Namoi River at Goangra 475 715 2007/2008 7 381 481

2008/2009 11 350 370

2009/2010 7 464 559

2010/2011 7 413 438

2011/2012 6 301 351

Gwydir 418058 Mehi River at Bronte 412 545 2007/2008 10 348 485

2008/2009 12 274 351

2009/2010 11 598 1040

2010/2011 12 315 538

2011/2012 11 430 709

NSW Border

Rivers

416001 Macintyre River at Mungindi 250 330 2007/2008 9 244 273

2008/2009 12 186 279

2009/2010 12 185 214

2010/2011 12 223 316

2011/2012 9 279 332

Barwon

Darling

425008 Darling River at Wilcannia

Main Channel

389 453 2007/2008 12 397 1150

2008/2009 11 237 279

2009/2010 12 197 304

2010/2011 10 256 344

2011/2012 12 336 647

Condamine

Balonne

422015 Culgoa River at Brenda 170 210 2007/2008 4 163 185

2008/2009 7 209 235

2009/2010 5 176 193

2010/2011 4 202 232

2011/2012 6 248 334

422030 Narran River at New

Angledool

160 210 2007/2008 4 225 868

2008/2009 4 239 249

2009/2010 4 223 241

2010/2011 3 202 237

2011/2012 6 207 332

Warrego 423004 Warrego River at Barringun No.2

101 110 No data available

423005 Cuttaburra Creek at Turra 100 130 No data available



Flow Conditions

Many water quality attributes are strongly correlated to river flow conditions. Flow during the

2007 to 2012 period was characterised by low flow from 2007 to 2010 with substantially higher

flows in all water quality zones from 2010 to 2012. Figures 10 to 21 illustrate the total annual

flow (ML/year) at selected gauging stations within each water quality zone during 2007 to 2012.

The use of total annual flow in these figures gives a general indication of river flow conditions in

each water quality zone. No attempt has been made in this report to assess individual results

against flow at the time of sampling or the timing of sampling in relation to high or low flow

events.

Zone A1- Condamine, Paroo Warrego (Lowland)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

500000

1000000

1500000

2000000

2500000

3000000

An

nu

al flo

w (

ML

/ye

ar)

Narran at New Angledool Culgoa at Brenda Paroo at Willara Crossing

Figure 10 Flow at selected gauging stations in the Condamine, Paroo and Warrego (lowland) water quality zone

Zone A2 - Border Rivers, Gwydir, Namoi (Lowland)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

200000

400000

600000

800000

1000000

1200000

1400000

1600000

An

nu

al flo

w (

ML

/ye

ar)

Barwon at Mungindi Mehi at Bronte Namoi at Goangra

Figure 11 Flow at selected gauging stations in the Border Rivers, Gwydir and Namoi (lowland) water quality zone



Zone A3 - Castlereagh, Lachlan, Macquarie, Murrumbidgee (Lowland)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

500000

1000000

1500000

2000000

2500000

An

nu

al flo

w (

ML

/ye

ar)

Murrumbidgee d/s Maude Weir Lachlan at Booligal Macquarie at Carinda Bogan at Gongolgan

Figure 12 Flow at selected gauging stations in the Castlereagh, Lachlan, Macquarie and Murrumbidgee (lowland) water quality zone

Zone B2 - Border Rivers, Gwydir, Namoi (Upland)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

400000

800000

1200000

1600000

2000000

An

nu

al flo

w (

ML

/da

y)

Macintyre at Holdfast Dumaresq at Glenarbon Weir Gwydir at Gravesend Namoi at Gunnedah

Figure 13 Flow at selected gauging stations in the Border Rivers, Gwydir and Namoi (upland) water quality zone

Zone B3 - Castlereagh, Lachlan, Macquarie, Murrumbidgee (Upland)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

1000000

2000000

3000000

4000000

5000000

6000000

An

nu

al flo

w (

ML

/ye

ar)

Murrumbidgee at Gundagai Lachlan at Forbes Macquarie at Dubbo

Figure 14 Flow at selected gauging stations in the Castlereagh, Lachlan, Macquarie and Murrumbidgee (upland) water quality zone



Zone B6 - Kiewa, Mitta Mitta, Upper Murray (Upland)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

500000

1000000

1500000

2000000

2500000

3000000

3500000

An

nu

al flo

w (

ML

/ye

ar)

Tooma at Pinegrove Murray at Bringenbong

Figure 15 Flow at selected gauging stations in the Kiewa, Mitta Mitta and Upper Murray (upland) water quality zone

Zone C2 - Border Rivers, Gwydir, Namoi (Montane)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

100000

200000

300000

400000

500000

An

nu

al flo

w (

ML

/ye

ar)

Severn at Strathbogie Gwydir at Yarrowyck Macdonald at Woolbrook

Figure 16 Flow at selected gauging stations in the Border Rivers, Gwydir and Namoi (montane) water quality zone

Zone C3 - Lachlan, Murrumbidgee (Montane)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

50000

100000

150000

200000

250000

An

nu

al flo

w (

ML

/ye

ar)

Murrumbidgee at Mittagang Crossing

Figure 17 Flow at a selected gauging station in the Lachlan and Murrumbidgee (montane) water quality zone



Zone cMum - Central Murray (Upper, Middle)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

2000000

4000000

6000000

8000000

10000000

An

nu

al flo

w (

ML

/ye

ar)

Edward at Deniliquin Murray at Barham Murray D/S Yarrawonga Weir Billabong at Jerilderie

Figure 18 Flow at selected gauging stations in the Central Murray (upper and middle) water quality zone

Zone cMl - Central Murray (Lower)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

4000000

8000000

12000000

16000000

20000000

An

nu

al flo

w (

ML

/ye

ar)

Murray at Lock 10 Wentworth

Figure 19 Flow at a selected gauging station in the Central Murray (lower) water quality zone

Zone Du - Darling (Upper)

1 2 3 4 50

1000000

2000000

3000000

4000000

5000000

6000000

7000000

An

nu

al flo

w (

ML

/ye

ar)

Barwon at Dangar Bridge Barwon at Brewarrina Barwon at Collarenebri

Figure 20 Flow at selected gauging stations in the Darling (upper) water quality zone



Zone Dml - Darling (Middle, Lower)

2007/2008 2008/2009 2009/2010 2010/2011 2011/20120

2000000

4000000

6000000

8000000

10000000

An

nu

al flo

w (

ML

/ye

ar)

Darling at Bourke Darling at Wilcannia Darling U/S Weir 32

Figure 21 Flow at selected gauging stations in the Darling (middle and lower) water quality zone



Discussion

Assessment of Basin Plan water quality targets

The Murray-Darling Basin has been divided into basic geographic units or zones to enable the

setting of water quality targets. These zones form a comparative tool that enables reporting of

water quality data by comparing similar water quality stations to a recognised target. It is

expected that data from groupings of water quality monitoring stations within a zone would

behave in a similar manner based on their geology, soil types and climatic conditions. Any

deviations from that similar pattern can then be explored further to determine the cause.

Where there was inadequate reference site data or locally derived guidelines for a zone during

the development of the Basin Plan, the target was based on the ANZECC Guidelines (2000) for

slightly modified waterways (Tiller and Newall 2010). This has had significant implications for the

reporting of water quality condition along the Darling River; with the illogical scenario of more

stringent targets in lower reaches compared to upstream catchments. The targets should

account for the trend of increasing sediment loads and nutrient concentrations with distance

down the catchment. Tiller and Newall (2010) identified the middle and lower zones of the

Darling River as a ‘hot spot’ in terms of turbidity and nutrients and suggested the proposed

targets may be too low and need refinement. When the water quality targets are adjusted so that

upper to middle and lower reaches of the Darling have the same target, only turbidity has been

rated as Very Poor in the Darling River.

In the Basin Plan, the middle and lower reaches of the Darling River are combined into one

zone. It could be expected that the water retention time in Menindee Lakes would allow the

settling of particulate matter, resulting in reduced turbidity, total phosphorus and total nitrogen in

the river downstream of the lakes. From the annual median data collated for this report, this

does not appear to be the case. The large shallow lakes that make up the Menindee Lakes

system are exposed to the wind and are well mixed. The re-suspension of fine sediments from

the bottom maintains high turbidity in the lakes. This turbid water is then released downstream.

For this reason it appears appropriate to use the same targets in the middle and lower zones of

the Darling.

If the development of separate water quality targets for the lower Darling is required in the future,

this information is now available through the current NSW water quality monitoring program.

Data paucity is still an issue in the middle Darling and other options could be explored to develop

targets in this zone. A long-term water quality program exists for the Menindee Lakes and this

data is also available to contribute to the interpretation of water quality in far western NSW.

There were two zone-catchment assessment units with Very Poor ratings; the Border Rivers,

Gwydir, Namoi montane zone (C2) and Macquarie lowlands zone (A3). The poor water quality

rating in the montane area of the Border Rivers, Gwydir and Namoi catchments is thought to be

driven by the basalt derived soils along the Great Dividing Range providing a source of nitrogen

and phosphorus, and an alkaline pH. These targets should be reviewed to better account for

local geology. The rivers of the lowlands of the Macquarie catchment have more in common with

the turbid, low flowing rivers of the Intersecting Streams than the Murrumbidgee. Future

assessments may show that the Basin Plan water quality targets for the Macquarie lowlands

should be brought into line with the Intersecting Streams (A1) rather than the more stringent

targets of zone A3.

When the same water quality targets of the lower Murrumbidgee and Lachlan Rivers were

applied to the Edward - Wakool Rivers and Billabong Creek, there was a wider range of water

quality ratings for sites within this new zone, with some still rated as Very Poor and other sites

ranging from Poor through to Good. This result provides a more accurate reflection of the range



of water quality and catchment conditions for these river systems. In this scenario, the central

Murray River remains as a separate zone with the original targets of the Basin Plan.

Scale of assessment

There is no clear direction within the Basin Plan as to how the water quality data are to be

interpreted or at what scale. The only guidance is that reporting is to be undertaken every five

years and that annual medians are to be assessed against the documented water quality zone

targets. The primary intent of the Basin Plan water quality targets is not to assess the

performance of individual sites, but to aggregate reporting up to a catchment or zone scale

(Brian Bycroft, Pers. Com. 2014). In this report annual medians have been calculated for each

site and reported individually as well as aggregated to provide a water quality rating for each

zone and zone-catchment unit.

The National Water Quality Management Strategy outlines a three tiered approach to water

quality management; national, state / territory and regional / catchment levels (ANZECC and

ARMCANZ 2000). The reporting against Basin Plan water quality targets should take into

account these three levels. Organisations operating at the region or catchment scale require site

specific information to assist with developing and targeting catchment management strategies.

Assessments at the zone scale will provide input for the development of water quality

management plans for water resource areas. At the national level, information developed for the

Basin Plan would provide sufficient detail to inform overarching guidelines for minimum water

quality standards. This report has attempted to meet the requirements of these three audiences.

The assessment of individual site data versus aggregated data did highlight similar water quality

degradation issues in some zones. However combining site data into large amalgamated

datasets to calculate zone ratings diluted the interpretation of water quality problems in some

areas, as the results from poorer sites are averaged out by sites with better water quality. This

could lead to water planning not focusing on problem areas, as a water quality issue will not be

obvious from the amalgamated data.

The assessment of individual site data highlighted the differences between the drier years (2007

to 2010) and the wetter years (2010 to 2012) which would be missed in a five year score. It is

recommended that future assessments continue to calculate and assess annual medians as well

as the five year score. It is also acknowledged that progress toward targets involves time lags

between changes to management resulting in changes to water quality. These long term

changes are unlikely to be detected in a five year reporting cycle.

As there are five jurisdictions in the Murray-Darling Basin, it is possible that each jurisdiction will

use different methods to compile and interpret data. There needs to be further discussion to

facilitate an agreement on how the water quality data should be interpreted and a reporting

structure to ensure continuity across state borders before the first five year report is due.

Flow conditions

Many water quality attributes are strongly correlated to flow. Generally high flow from rainfall and

runoff results in higher turbidity and nutrient concentrations but possibly lower dissolved oxygen.

River flow during the 2007 to 2012 period was characterised by low flow across the state from

2007 to 2010, with substantially higher flows in all water quality zones from 2010 to 2012. Low

flows during the study period would have minimised erosion processes, assisting in lowering

turbidity and nutrient levels from 2007 to 2010. Major flooding in the Murray and Murrumbidgee

Rivers and in the northern Basin in 2011, resulted in blackwater events in these catchments. An

analysis of results at shorter time intervals than annual and five yearly would incorporate more

flow variability into the assessment of water quality.

The Basin Plan water quality targets were developed using data collected from 1991 through to

2009 to try and incorporate a spread of climatic and flow conditions (Tiller and Newall 2010). It

was noted that although the time period covered a range of conditions, the data used was



primarily collected at base or low flow and generally missed high flow and flood events. In this

report, turbidity, total phosphorus and total nitrogen all exceeded their respective targets more

frequently in the higher flow years of 2010 to 2012 than in the preceding drier years of 2007 to

2010. The assessment data should match the conditions of the reference dataset used to derive

the targets, allowing the comparison of like data. Water quality targets that are flow partitioned or

flow modelled may need to be derived for future assessment. Until then, assessments against

the Basin Plan targets must note that they refer to low flow conditions and are likely to be

exceeded in wetter years.

The ephemeral nature of the Intersecting Streams raises the issue of samples only being

collected from these sites during or immediately after heavy rainfall and following flood events in

the catchment area. Any analysis should be mindful of this as the use of a few data points

collected from a site during high flows may result in erroneous interpretation of results. If it is

common practice to sample high flows due to the streams ephemeral nature, then the water

quality targets need to take this into account. For future assessments, water quality targets that

are flow partitioned or flow modelled may need to be derived for ephemeral streams.

National water quality guidelines for the protection of aquatic ecosystems

The national water quality guidelines (ANZECC Guidelines 2000) provide default trigger values

for slightly disturbed ecosystems and use altitude to delineate the river systems into alpine

(>1500 m), upland (150 to 1500 m) and lowland streams (



No assessment was made as to whether the data points were spread throughout the year or

clumped around a single flow event. In ephemeral streams, it may not be possible to have a

spread of data points throughout the year. The number of samples in a year required for

confident reporting against the Basin Plan water quality targets needs further development.

The water quality data used in this report were compiled from 115 water quality monitoring

stations located within the Murray-Darling Basin. These monitoring stations have not been

selected to directly assess the Basin Plan water quality targets, but rather to provide long term

data to assess river water quality condition and trend reporting. Water quality monitoring sites

are usually located at or in close proximity to existing flow gauging stations so that flow data can

be used in the interpretation of water quality results.

As gauging stations are often located lower in the catchments to assist in flood warning /

forecasting, managing water releases and flow modelling, some of the high altitude zones (e.g.

Lachlan, Murrumbidgee upland zone (C3) and Mitta Mitta, Upper Murray montane zone (C6))

are poorly represented. Inversely, the upland zones of the Border Rivers, Gwydir, Namoi (B2)

and Castlereagh, Lachlan, Macquarie and Murrumbidgee (B3) catchments are very well

represented with 30 and 27 monitoring sites respectively. There were no monitoring sites located

in the lower Murray (lM) or Mitta Mitta and Upper Murray montane (C6) zones for this study.

Current water quality monitoring and reporting programs should be reviewed to include

additional monitoring sites in the upland and montane zones and the lower Murray to achieve

better spatial representativeness of sites and avoid bias in water quality zones.

State-wide summary of water quality characteristics

Turbidity

The amount of suspended sediment in water is generally related to the intensity of human

activity in the catchment, such as land clearing, accelerated erosion from agricultural land,

stream banks or channels, the dispersive nature of the soil and localised issues such as stock

access. High turbidity is often associated with increased flow following storm events. Other

pollutants such as heavy metals, nutrients, bacteria and pesticides can be transported into and

down river systems attached to suspended sediments.

Turbidity should be measured immediately without altering the original sample conditions such

as temperature and pH (APHA 1995). Field turbidity is more representative of instream

conditions and should be used in preference to laboratory measurement (Buckland et al. 2008).

Buckland et al. (2008) reported laboratory measurements to be around 30% to 40% lower than

field measurements. Assessing the Excel Data Spreadsheet file (Tiller and Newall 2010), it

appears that a mixture of both field and laboratory turbidity data has been used in the

development of zone targets for some sites. The difference between field and laboratory data

means that the two data sets should not be combined, especially at sites in catchments with high

turbidity.

Laboratory turbidity data is often used for reporting as it is most likely to have the longest period

of record. A comparison of the laboratory and field turbidity medians shows that five of the 12

zones had a poorer rating for field turbidity than laboratory turbidity. This suggests that the 30%

to 40% difference between laboratory and field results can be the difference between zones

meeting or exceeding the Basin Plan turbidity targets. It is recommended that for future data

analysis, field turbidity data is used to calculate annual median turbidity in preference to

laboratory data.

Some sites were rated as Very Poor largely due to local catchment conditions. Coxs Creek at

Boggabri (419032) is located on the Liverpool Plans which has been highly modified for

agricultural production (Mawhinney 2011). The Weir River at Talwood (416202) has very fine

sediments which remain in suspension, even under low or zero flow conditions. The turbidity



targets may never be met at these sites and local site specific targets should be developed, as

outlined in the Basin Plan.

Total Phosphorus

Sources of nutrient contamination include effluent from sewage treatment works, farms and

industry, and runoff from agricultural land and urban storm water. Phosphorus and nitrogen are

the main nutrients of concern in freshwater ecosystems. Nutrients can be dissolved, bound

within sediments, or adsorbed onto suspended material (i.e. soil or organic matter).

The main transport mechanism for the movement of phosphorus is attached to suspended

material. Generally, as flow increases due to catchment runoff, so does the concentration of

phosphorus. Due to drought and low flow reducing the mobilisation of phosphorus from the

catchment, there were less exceedences between 2007 and 2010. During the wetter years from

2010 to 2012, the median total phosphorus concentration at most sites exceeded the zone

targets. Five zones still rated as Very Good during high flow years, indicating that either the total

phosphorus concentration in these zones was not affected by increased flow, or that the targets

for these zones are high.

As for turbidity, the total phosphorus target for the Darling - middle, lower zone (Dml) is lower

than the target for the zone immediately upstream. The total phosphorus target for the middle

and lower Darling is 50 µg/L, while the target for the zone immediately upstream (upper Darling)

is 250 µg/L. Again, it is preferable to adopt the target for the zone immediately upstream rather

than the ANZECC Guidelines (2000) default trigger value in this circumstance. If the target for

the Darling - middle, lower zone was 250 µg/L, sites would have passed in the dry years and

failed in the wet years, similar to other zones across the Basin.

The Liverpool Plains are recognised as the largest dryland summer cropping area in NSW and

the alluvial clay soils in this catchment are naturally high in phosphorus (Banks 1995). As these

soils are eroded into the river system by floods and runoff events, the associated phosphorus is

transported downstream. Despite ongoing land management activities, the total phosphorus

concentrations will continue to remain high in the river systems in this catchment and are

unlikely to improve in the short term. The Liverpool Plains should have a separate target from

the rest of the Border Rivers, Gwydir and Namoi upland zone (B2). The high concentrations of

phosphorus from the Liverpool Plains also impacts upon Narrabri Creek at Narrabri (419003)

which is located at the bottom of zone B2 at the boundary with the Border Rivers, Gwydir and

Namoi lowland zone (A2).

There is a cluster of sites rated as Very Poor located upstream of Wagga Wagga in the

Murrumbidgee Catchment. These sites include:

Adjungbilly Creek at Darbalara (410038);

Muttama Creek at Coolac (410044);

Adelong Creek at Bereena (41010890);

Hillas Creek at Mundarlo Road Bridge (41010809), and

Tarcutta Creek at Old Borambola (410047).

The target for most of these sites is 35 µg/L, except for Tarcutta Creek at Old Borambola

(410047) which is 50 µg/L. All of these stations are located at the end of smaller catchments.

The soils in these catchments are mostly less fertile types derived from granites and

metasediments (OEH 2013). Historically, the streams in this area were the focus of significant

mining and fossicking activities. These activities and the ongoing stream bank erosion of the

alluvial soils along the stream lines could be providing a source of phosphorus for these

streams.



The total phosphorus target for the Border Rivers, Gwydir and Namoi montane zone (C2) should

be investigated further. The Basin Plan target for this zone is 20 µg/L. There are large areas of

basalt derived soils located along the top of the Great Dividing Range in this zone, resulting in

elevated phosphorus concentrations. Tiller and Newall (2010) assigned a low confidence to the

water quality targets for this zone. This target should need to be revised based on a modelling

approach using soil types.

Total Nitrogen

As nitrogen and phosphorus are often transported via similar mechanisms (i.e. attached to soil

or organic p

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