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Namoi Water Quality Project 2002-2007 Final report

Publisher

NSW Office of Water

Level 17, 227 Elizabeth Street GPO Box 3889 Sydney NSW 2001

T 02 8281 7777 F 02 8281 7799

[email protected]

www.water.nsw.gov.au

The NSW Office of Water is a separate office within the Department of Environment, Climate Change and Water. The Office of Water manages the policy and regulatory frameworks for the State’s surface water and groundwater resources to provide a secure and sustainable water supply for all users. The Office of Water also supports water utilities in the provision of water and sewerage services throughout New South Wales.

Namoi Water Quality Project 2002-2007 – Final report

March 2011

ISBN 978 1 74263 160 8

This publication may be cited as:

Mawhinney, W. (2011), Namoi Water Quality Project 2002-2007 – Final report, NSW Office of Water, Sydney

© State of New South Wales through the Department of Environment, Climate Change and Water, 2011

This material may be reproduced in whole or in part for educational and non-commercial use, providing the meaning is unchanged and its source, publisher and authorship are clearly and correctly acknowledged.

Disclaimer: While every reasonable effort has been made to ensure that this document is correct at the time of publication, the State of New South Wales, its agents and employees, disclaim any and all liability to any person in respect of anything or the consequences of anything done or omitted to be done in reliance upon the whole or any part of this document.

NOW 11_032

Namoi Water Quality Project 2002–2007: Final report

Contents

Abstract.................................................................................................................................................. 1

1. Introduction........................................................................................................................................ 2

1.1 Catchment description............................................................................................................. 2

1.2 Landuse................................................................................................................................... 3

2. Methods............................................................................................................................................. 3

2.1 Site selection ........................................................................................................................... 3

2.2 Attribute selection.................................................................................................................... 4

2.3 Sampling and laboratory methods .......................................................................................... 8

2.3.1 Quality Assurance/Quality Control ............................................................................. 8

2.3.2 Replicate samples...................................................................................................... 8

2.4 Statistical analysis ................................................................................................................... 9

3. Results and discussion...................................................................................................................... 9

3.1 Sampling site conditions ......................................................................................................... 9

3.2 Salinity................................................................................................................................... 10

3.3 Continuous electrical conductivity monitoring ....................................................................... 13

3.4 Major ions.............................................................................................................................. 16

3.5 Turbidity................................................................................................................................. 18

3.6 Nutrients ................................................................................................................................ 21

3.6.1 Total phosphorus ..................................................................................................... 21

3.6.2 Total nitrogen ........................................................................................................... 24

3.7 Pesticides .............................................................................................................................. 26

3.7.1 Insecticides .............................................................................................................. 27

3.7.2 Herbicides ................................................................................................................ 28

4. Summary and conclusions .............................................................................................................. 32

5. Future water quality monitoring ....................................................................................................... 33

6. References ...................................................................................................................................... 34

Appendix 1 - Pesticides screened for Namoi Water Quality Project ................................................... 36

Appendix 2 - NSW Office of Water, laboratory water analysis methods............................................. 38

Appendix 3 - Summary statistics for basic water quality data by site ................................................. 39

i | NSW Office of Water, March 2011

Tables

Table 1: Upland sampling sites and indicators for the NWQP .............................................................. 5

Table 2: Lowland sampling sites and indicators for the NWQP ............................................................ 5

Table 3: Water quality guidelines – electrical conductivity (from ANZECC/ARMCANZ, 2000b) ........ 10

Table 4: Number and percentage of days where electrical conductivity exceeded Namoi end of valley salinity targets and water quality guidelines (Namoi River at Goangra)........... 16

Table 5: Number and percentage of detections of common pesticides in the Namoi Catchment from 1991-1992 through to 2006-2007......................................................... 31

Figures

Figure 1: Location of NWQP sampling sites.......................................................................................... 7

Figure 2: Box plots of electrical conductivity (µS/cm) readings in the upper Namoi Catchment

from July 2002 to June 2007........................................................................................... 11

Figure 3: Box plots of electrical conductivity (µS/cm) readings in the lower Namoi Catchment from July 2002 to June 2007........................................................................................... 12

Figure 4: Comparison of 2002-2007 electrical conductivity (µS/cm) readings in the upper Namoi Catchment with 1990-2000 historical data .......................................................... 12

Figure 5: Comparison of 2002-2007 electrical conductivity (µS/cm) readings in the lower

Namoi Catchment with 1990-2000 historical data .......................................................... 13

Figure 6: Time series plot of flow (ML/day) and electrical conductivity (µS/cm) for Narrabri Creek at Narrabri (419003) from July 2002 to July 2007................................................ 14

Figure 7: Time series plot of flow (ML/day) and electrical conductivity (µS/cm) for Narrabri Creek at Narrabri (419003) for December 2004............................................................. 14

Figure 8: Cumulative monthly salt loads for the Namoi River at Goangra .......................................... 15

Figure 9: Piper diagram of major ions data from selected sites in the Namoi Catchment .................. 17

Figure 10: Box plots of turbidity (NTU) readings in the upper Namoi Catchment from July 2002 to June 2007 .......................................................................................................... 19

Figure 11: Box plots of turbidity (NTU) readings in the lower Namoi Catchment from July 2002 to June 2007 .......................................................................................................... 19

Figure 12: Comparison of 2002-2007 turbidity (NTU) readings in the upper Namoi Catchment

with 1990-2000 historical data ........................................................................................ 20

Figure 13: Comparison of 2002-2007 turbidity (NTU) readings in the lower Namoi Catchment with 1990-2000 historical data ........................................................................................ 20

Figure 14: Box plots of total phosphorus (mg/L) readings in the upper Namoi Catchment from July 2002 to June 2007................................................................................................... 22

Figure 15: Box plots of total phosphorus (mg/L) readings in the lower Namoi Catchment from

July 2002 to June 2007................................................................................................... 22

Figure 16: Comparison of 2002-2007 total phosphorus (mg/L) readings in the upper Namoi Catchment with 1990-2000 historical data...................................................................... 23

ii | NSW Office of Water, March 2011

iii | NSW Office of Water, March 2011

Figure 17: Comparison of 2002-2007 total phosphorus (mg/L) readings in the lower Namoi Catchment with 1990-2000 historical data...................................................................... 23

Figure 18: Box plots of total nitrogen (mg/L)) readings in the upper Namoi Catchment from

July 2002 to June 2007................................................................................................... 24

Figure 19: Box plots of total nitrogen (mg/L)) readings in the lower Namoi Catchment from July 2002 to June 2007................................................................................................... 25

Figure 20: Comparison of 2002-2007 total nitrogen (mg/L) readings in the upper Namoi Catchment with 1990-2000 historical data...................................................................... 25

Figure 21: Comparison of 2002-2007 total nitrogen (mg/L) readings in the lower Namoi

Catchment with 1990-2000 historical data...................................................................... 26

Figure 22: Box plot of total endosulfan concentrations in pesticide samples collected downstream of Keepit Dam from 1991-1992 to 2006-2007............................................ 28

Figure 23: Box plot of total atrazine concentrations in pesticide samples collected downstream of Keepit Dam from 1991-1992 to 2006-20007.......................................... 29


Abstract

Water quality is an important indicator of catchment health. It reflects everything that happens in an area. Runoff from cropping areas, erosion of soil and associated nutrients from stream channels and

banks and discharge from saline areas can degrade water quality in terms of sedimentation, turbidity, salinity, enhanced nutrient load and insecticide and herbicide residues.

The Namoi Water Quality Project (NWQP) was a five year monitoring program, commencing in July

2002. Physical and chemical basic water quality attributes, including electrical conductivity, turbidity, total suspended solids, total nitrogen and total phosphorus, were monitored on a monthly basis at a total of 29 sites. Pesticide samples were also collected from sites located in major irrigation and

dryland farming areas of the Namoi Valley.

The 2002-2007 period was characterised by dry climatic conditions and extended periods of low or zero flows. Total annual salt loads in the Namoi River at Goangra were lower than the NSW Salinity

Strategy end of system target, attributed to these low flows during the sampling period.

The majority of sites had median electrical conductivity results that did not meet Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council

of Australia and New Zealand (ANZECC and ARMCANZ, 2000a) default trigger values for the protection of aquatic ecosystems (in upland and lowland rivers) of South-eastern Australia, yet remained suitable for irrigation.

High median total phosphorus and total nitrogen concentrations, in excess of the ANZECC and ARMCANZ (2000a) default trigger values, in conjunction with the low flows experienced during the sampling period, provided favourable conditions for the growth of potentially toxic blue-green algae.

However, results from algal monitoring programs show that high blue-green algae biovolumes in rivers did not eventuate to the extent suggested by the high nutrient levels, indicating other factors such as turbidity and light availability were not suitable for bloom formation.

Endosulfan, an insecticide found regularly in previous water quality programs, was detected in the Namoi Catchment in January 2005 following minor flooding in the lower catchment. This was the first time endosulfan residues had been detected in the Namoi Valley since the 2000-2001 cotton growing

season.

Residues of the herbicide atrazine continue to be detected at a variety of sites, with the majority from two sites on the Liverpool Plains, the Mooki River at Ruvigne and Coxs Creek at Boggabri. More work

is required to reduce the movement of this herbicide into our waterways, particularly in dryland cropping areas.

1 | NSW Office of Water, March 2011


1. Introduction

A number of water quality monitoring and river health assessment projects have been undertaken in the Namoi Catchment over the past 30 years (Key Sites WQ Program – Preece, 1998; Liverpool

Plains WQ project - Mawhinney, 1998a; Riverine condition assessment of the Namoi catchment – Foster et al., 2000; Central and North West Region WQ Project - Muschal, 2001). A review of the outcomes of these various projects provided natural resource managers with a suite of river health

issues and information needs. These were deliberated and prioritised by key stakeholders in the Namoi Catchment, including state agency staff, the then Namoi Catchment Management Board and water quality managers. Identifying these key issues and information needs enabled clear objectives

for water quality monitoring to be established. The objectives of the Namoi Water Quality Project (NWQP) were to:

• monitor and describe the water quality of the creeks and rivers of the Namoi Catchment;

• provide data for the assessment of trends in water quality (improving /declining);

• provide data which assists with the setting of future water quality guidelines and trigger

values, and

• highlight areas that require further investigation, as they become apparent.

These objectives were used to develop the study design, following methodology outlined in the Australian Guidelines for Water Quality Monitoring and Reporting (ANZECC and ARMCANZ, 2000a).

The purpose of this report was to present the water quality data collected for the Namoi Water Quality

Project for the period July 2002 to June 2007 and to provide a five year assessment of water quality against aquatic ecosystem health, irrigation use guidelines and Namoi River end of valley salinity targets. Water quality data has also been compared to historical data, where it was available, to

provide some indication of what is ‘normal’ for each site and provide a visual assessment of change over time.

1.1 Catchment description

The Namoi Catchment is located in northern New South Wales and forms part of the Murray-Darling Basin. The catchment is approximately 43 000 km2 in area and extends from the Great Dividing Range in the east to the Barwon River in the west. The Namoi River and its tributaries flow predominantly in a

westerly direction from the highest point in the catchment at 1400 metres down to 120 metres at the junction with the Barwon River at Walgett. The main tributaries are the Peel and Mooki Rivers and Coxs Creek. The Namoi Catchment is predominantly flat, with nearly two thirds having a land slope of

less than three degrees. Downstream of Keepit Dam, valley slopes decrease dramatically and the valley floor widens. Streams are more gently flowing, with fine grained to sandy beds and large floodplain surfaces (Lampert and Short, 2004). Downstream of Narrabri, the extensive floodplain is

unconstrained and contains features such as billabongs, anabranches, effluent channels, in-stream benches and small floodplain wetlands. The main effluent stream in the lower catchment is Pian Creek which receives stock and domestic flows from Gunidgera Weir near Wee Waa.



The natural flow pattern of the Namoi River has been altered by the construction of three major

storages which are used mainly to supply water for irrigation and stock and domestic use. These are:

• Chaffey Dam (62 000 ML) on the Peel River near Tamworth;

• Split Rock Dam (397 000 ML) on the Manilla River near Manilla, and

• Keepit Dam (427 000 ML) on the Namoi River near Gunnedah.

Annual rainfall is highly variable between years and seasons, with variability increasing towards the west. Yearly average rainfall ranges from 460 mm at Walgett to more than 1000 mm on parts of the

Great Dividing Range. There is a slight summer dominant rainfall, though flooding can occur at any time of the year.

1.2 Landuse

The majority of the land area of the Namoi Catchment is used for sheep and cattle grazing. This is predominately on the tablelands, less fertile slopes and the western areas where cropping is unreliable and opportunistic. The highest value agricultural enterprise in the catchment is cotton production.

Other significant crops include wheat, barley, sorghum, lucerne and hay production. The cropping regime on the flatter country is generally continuous. The Liverpool Plains are recognised as the largest dryland summer cropping area in NSW, and the clay soils are considered to be some of the

most productive agricultural soils in Australia.

Information gathered for the Liverpool Plains Water Quality Project (Mawhinney, 1998a) suggested that the decline in water quality on the Liverpool Plains has coincided with the expansion of

agriculture. Large areas of native vegetation have been replaced by annual crops, leaving soils prone to erosion and increasing the amount of water leaking through the soil profile into saline watertables. The expansion of cropping in the region has coincided with the detection of high concentrations of

nutrients, sediment and pesticide residues in some waterways and highly saline watertables rising in some areas in response to recharge events, causing soil salinity.

2. Methods

2.1 Site selection

Water quality was monitored on a monthly basis at 29 sites in the Namoi Catchment (see Figure 1 for site locations). Numerous factors were taken into consideration during the site selection process.

These included:

• consideration of sites with a history of water quality data to maintain a continuous data set to

enable trend analysis;

• consideration of sites located at or near a New South Wales Office of Water flow gauging

station to assess the impact of flow on water quality and undertake load calculations;

• choosing sites with safe access in all weather conditions;

• consideration of sites in locations where samples could be collected where the water in the river is mixed and away from the direct influence of point source pollution;

• consideration of sites chosen to provide data for Riverine Condition and Assessment

reporting (Foster et al., 2000) with preference given to sites located at the bottom of each of



the respective sub catchments (as identified in the Stressed Rivers Assessment Report,

1999);

• consideration of sites in upland river reaches to characterise trends in less developed

catchments,

The final site selection was delineated by logistical and financial factors and the sites most representative of the above considerations.

The Namoi Catchment has been divided into upland and lowland zones based on the variation in altitude, changes to river geomorphology and the different mix of agricultural production. The upper catchment includes sites from the top of the Great Dividing Range to the junction of the Peel and

Namoi Rivers immediately below Keepit Dam. The lowland sites include those on the Liverpool Plains and from Gunnedah to the junction with the Barwon River at Walgett. This also allows applicability of the default Water Quality Guidelines which have upland and lowland values.

2.2 Attribute selection

Indicator variables for the NWQP were chosen to build on existing long term datasets, to enable the

assessment of trends in water quality for riverine condition assessment. The indicators needed to be easily sampled, measured, preserved, analysed and cost effective. Previous water quality programs (Mawhinney, 1998a; Gordon, 2001; Muschal, 2001) have shown the main water quality issues in the

region are:

• eutrophication, characterised by excessive nutrient loading;

• salinity;

• suspended sediment and turbidity, and

• runoff containing agricultural chemicals.

All sites were monitored for basic water quality attributes, namely electrical conductivity, turbidity, total

nitrogen and total phosphorus. Pesticide samples were collected from lowland sites (between Gunnedah and Walgett) where there is an increased risk of agricultural chemical contamination (list of pesticides in Appendix 1). Major ions (sodium (Na+), calcium (Ca2+), potassium (K+), magnesium

(Mg2+), bicarbonate (HCO3-), sulphate (SO4

2-) and chloride (Cl-)) and total dissolved solids were monitored at sites where continuous electrical conductivity probes had been installed at Office of Water flow gauging stations. Tables 1 and 2 list the sampling sites and the attributes monitored.



Table 1: Upland sampling sites and indicators for the NWQP

Site number

from Figure 1

Office of Water

Station Number

Station Name Flow Sample Type

1 419004 Peel River at Bowling Alley Point Unregulated Basic WQ

2 419045 Peel River downstream Chaffey Dam

Regulated Basic WQ

3 419024 Peel River at Paradise Weir Regulated Basic WQ, major ions, total dissolved solids

4 419073 Peel River at Appleby Crossing Regulated Basic WQ

5 419006 Peel River at Carroll Gap Regulated Basic WQ

6 419016 Cockburn River at Mulla Crossing Unregulated Basic WQ

7 419097 Goonoo Goonoo Creek at Meadows Lane

Unregulated Basic WQ, major ions, total dissolved solids

8 419031 Manilla River at Glen Riddle Unregulated Basic WQ

9 419043 Manilla River downstream Split Rock Dam

Regulated Basic WQ

10 419071 Macdonald River at Bendemeer Unregulated Basic WQ

11 419011 Namoi River at Manilla Weir Unregulated Basic WQ

12 419022 Namoi River at Manilla Railway Bridge

Regulated Basic WQ

13 419007 Namoi River at Keepit Regulated Basic WQ

Table 2: Lowland sampling sites and indicators for the NWQP

Site number

from Figure 1

Office of Water

Station Number


14 419027 Mooki River at Breeza Unregulated Basic WQ

15 419084 Mooki River at Ruvigne Unregulated Basic WQ, pesticides, major ions, total dissolved solids

16 419033 Coxs Creek at Tambar Springs Unregulated Basic WQ

17 419032 Coxs Creek at Boggabri Unregulated Basic WQ, pesticides, major ions, total dissolved solids

18 419001 Namoi River at Gunnedah Regulated Basic WQ, pesticides, major ions, total dissolved solids

19 419051 Maules Creek at Avoca East Unregulated Basic WQ

20 419905 Bohena Creek at Newell Highway Unregulated Basic WQ

21 419003 Narrabri Creek at Narrabri Regulated Basic WQ, pesticides, major ions, total dissolved solids

22 419039 Namoi River at Mollee Regulated Basic WQ




Site number

from Figure 1

Office of Water

Station Number


23 419059 Namoi River downstream Gunidgera Weir

Regulated Basic WQ, pesticides

24 419064 Pian Creek at Rossmore Regulated Basic WQ, pesticides

25 419049 Pian Creek at Waminda Regulated Basic WQ, pesticides

26 41910222 Baradine Creek at Coonamble Road Unregulated Basic WQ

27 419021 Namoi River at Bugilbone Regulated Basic WQ, pesticides

28 419026 Namoi River at Goangra Regulated Basic WQ, pesticides, major ions, total dissolved solids

29 419057 Namoi River at Walgett Regulated Basic WQ, pesticides


Figure 1: Location of NWQP sampling sites



2.3 Sampling and laboratory methods

Manual grab samples were collected at sites during the first whole week of each month. Efforts were made to try and collect samples from a site at the same time of day, on each sampling occasion, to

minimise statistical variation (e.g. diurnal cycles) and allowing clearer identification of trends.

Samples were collected from the stream edge with the aid of a telescopic sampling pole to reach the main flow of the river. Bottles were inverted and submerged to a depth of 25 cm from the water

surface or mid-depth of the water column in shallow waters less than 50 cm deep. Bottles were then turned right way up to fill.

Pesticide samples were collected in acid rinsed amber bottles with a silver foil insert in the lid. All other

samples were collected in new polyethylene bottles which were triple rinsed in-situ (including lids) prior to the sample being taken. All samples were immediately chilled to about 4°C. Total nutrient samples were frozen within eight hours of collection. The samples were analysed at the National Association of

Testing Authorities, Australia (NATA) accredited Office of Water, Water Environment Laboratory, located at Wolli Creek (see Appendix 2 for water analysis methods).

Sampling continued at many sites after the waterway had ceased to flow due to extended dry periods.

It was assumed that there may still be some degree of subsurface flow connecting pools and it was at the discretion of the sampling officer when the body of water no longer represented a true indication of overall water quality.

2.3.1 Quality Assurance/Quality Control

Consistent quality assurance/quality control (QA/QC) procedures produce data of known quality. Quality assurance (QA) is a plan that describes the measures used to produce data of known precision such as written procedures, work instructions, training requirements and record keeping.

Quality control (QC) procedures are a set of measures to ensure that the information collected is accurate and precise, and is recorded and reported in an approved manner.

The following QA/QC procedures for the NWQP include but are not limited to:

• field staff trained in sampling procedures. Field instruments are calibrated prior to each sampling run and details recorded in the calibration log book. Sample log sheets are filled

out at the time of sampling to provide sampling details, results of field measurements and any comments. Sampling locations, access details and attributes required are clearly identified in the Namoi Water Quality Project Operations Manual (Mawhinney, 2003a);

• sample log sheets form part of the sample custodianship procedure. One copy of the sheet

is sent to the Project Manager and another with the samples to the NSW Office of Water, Water Environmental Laboratory, and

• the data is audited by the Project Manager following the NSW Office of Water quality system procedure.

2.3.2 Replicate samples

Field sampling QA/QC was addressed through the collection of replicate samples. Replicate samples were collected to determine the magnitude of errors between sampling and sample analysis. Two

samples from the same site were analysed separately to establish the reproducibility of sampling. Replicate samples were collected, comprising a full suite, from the Namoi River at Goangra (419026). Replicate data was assessed during the data audit process.



2.4 Statistical analysis

Four water quality attributes (electrical conductivity, turbidity, total nitrogen and total phosphorus) have been compared to historic data (where available) and the Australian and New Zealand Guidelines for

Fresh and Marine Water Quality (ANZECC and ARMCANZ, 2000b) default trigger values for the protection of aquatic ecosystems in upland and lowland rivers in South-eastern Australia. Trigger values are alert levels above which action should be taken to assess if there is a potential impact.

Electrical conductivity has also been compared to the Namoi River end of valley targets set by the New South Wales Salinity Strategy (DLWC, 2000) and irrigation water guidelines (ANZECC and ARMCANZ, 2000b). Endosulfan and atrazine, two agricultural chemicals of concern in the regions

waterways, have been compared to the ANZECC and ARMCANZ (2000b) ecosystem protection guidelines.

Graphical techniques were used to describe spatial trends in the Namoi Catchment. Box and whisker

plots indicating the median (solid horizontal line within box), 25th and 75th

percentiles (boundary of box) and 10th

and 90th percentiles (whiskers above and below box) were used to summarise data. The data for the five year sampling period for each site was also compared to an historical ten year data set,

where the data were available for the site. The ten year data set included all routine water quality data collected between July 1990 and June 2000. All box and whisker plots were compiled in STATISTICA®.

Temporal trend analysis was not undertaken in this report due to the relatively short time frame of the project and the severe drought conditions for much of the sampling period would have influenced the results.

Baradine and Bohena Creeks are ephemeral streams flowing out of the Pilliga Forest. During monitoring over the five year sampling period, a total of ten and five samples respectively were collected from sites on these two creeks, always following heavy rainfall in the catchment area. It was

deemed that these samples did not truly represent routine samples and should not be used for riverine condition assessment. For this reason the data from these two sites have not been included in the analysis. Summary statistics for these sites have been included in Appendix 3.

3. Results and discussion

3.1 Sampling site conditions

The 2002-2007 sampling period was characterised by continuing dry conditions. There was moderate

flooding in the Peel and Cockburn Rivers in January 2004 peaking at 92 000 ML/day at Tamworth. Results from flood sampling during this event were reported by Mawhinney (2005). Minor flooding occurred in the Namoi River downstream of Boggabri, Wee Waa and in the Pilliga Forest in December

2004. The Namoi River at Mollee (located downstream of Narrabri) peaked at 112 000 ML/day during this second event. Apart from these two events, flows in the regulated rivers were mainly irrigation and stock and domestic releases from the major storages.

Many water quality attributes are strongly correlated to flow. Generally high flow from rainfall and runoff results in higher turbidity, nutrients and possibly pesticides, but lower electrical conductivity. Under these high flow conditions, the higher concentrations of pollutants are derived from diffuse

sources. Due to the low flow conditions experienced during this project, the contribution of pollution from point sources may have increased relative to diffuse sources and also increasing within site variability of pollution concentrations, as there was less dilution of point source pollutants by river flow.



3.2 Salinity

Salinity is the presence of dissolved salts in soil and water and is a problem common to many parts of Australia. It may be caused by the presence of salt in underlying soil or bedrock released by

weathering, salt deposited during past marine inundation of an area, or salt particles being carried over the land surface from the ocean. Australia’s arid climate provides insufficient rainfall to dilute the high levels of salt in the landscape. This has been further exacerbated by the increased mobilisation of

salts by activities such as land clearing, mining and irrigation. The most common measurement of the salinity of water is electrical conductivity, measured in microSiemens per centimetre (µS/cm). Electricity is conducted more easily through water (and therefore electrical conductivity rises) as the

concentration of dissolved salt increases. The National Water Quality Management Strategy gives numerous electrical conductivity guidelines depending on the proposed use of the water (ANZECC and ARMCANZ, 2000b). These guidelines are summarised in Table 3.

Table 3: Water quality guidelines – electrical conductivity (from ANZECC/ARMCANZ, 2000b)

Purpose Value (µS/cm) Comment

Default Trigger value for protection of aquatic environment – upland

350

Default trigger value for protection of aquatic environment - lowland

300

Irrigation water - Very low salinity rating * < 650

Irrigation water - Low salinity rating* 650 - 1300 Adopted by Namoi CMA as a river salinity management target in their Catchment Action Plan (2007)

Irrigation water - Medium salinity rating* 1300 - 2900

Irrigation water - High salinity rating* 2900 - 5200

Drinking water - Cattle < 5970 No adverse effects expected

Drinking water - Sheep < 7460 No adverse effects expected

Drinking water - Human 780 Based on taste

* This is a general guide as the impact of saline irrigation water on crops varies greatly due to the wide range of crop tolerances to salinity, irrigation method, soil properties and growth stage of the plant.

During the five year study most of the sites in the upper catchment had a median electrical

conductivity level above the ANZECC and ARMCANZ (2000b) default aquatic environment protection trigger value of 350 µS/cm (Figure 2). The Peel River at Appleby Lane and Carroll Gap and Goonoo Goonoo Creek at Meadows Lane had the highest median electrical conductivity, and were the only

sites to have medians above the minimum value of the low salinity guideline range for irrigation water. The Peel River gradually increased in electrical conductivity with distance downstream due to the influences of saline inflows from Goonoo Goonoo, Timbumburi and Tangaratta Creeks which enter the

Peel River downstream of Tamworth (Mawhinney, 2003b). The Macdonald River at Bendemeer had the lowest conductivity readings due to its location close to the top of the catchment in an area with minimal dryland salinity issues.

Three of the sites on the Liverpool Plains (Mooki River at Breeza and Ruvigne, and Coxs Creek at Tambar Springs) had the highest electrical conductivities of the 16 lowland sites (Figure 3), with many samples exceeding the lower value of the medium salinity range for irrigation water of 1300 µS/cm.

The majority of sites in the key irrigation areas downstream of Gunnedah were below the low salinity level for irrigation water.

In most cases the 2002-2007 median and range of electrical conductivity results in the upper

catchment were similar to the historical data (Figure 4). The Peel River at Bowling Alley Point had a much lower median electrical conductivity between 2002 and 2007. In this case saline springs in the



catchment may have stopped flowing, cutting off saline baseflow. The inverse could be occurring in the Manilla River at Glen Riddle, where saline springs continued to flow and salts were not diluted by rainfall, resulting in higher electrical conductivity readings. The Mooki River at Ruvigine had a much

higher median and range of results during the NWQP compared to the historical data (Figure 5). This is likely a consequence of salts being concentrated in the large pool at this sampling site by evaporation. Consistent electrical conductivity in the Namoi River may be a result of river regulation,

with water of consistent electrical conductivity released over time from Keepit Dam dominating flow in the river.

Figure 2: Box plots of electrical conductivity (µS/cm) readings in the upper Namoi Catchment from July 2002 to June 2007

Peel

at

Bow

l Alle

y Pt

Peel

d/s

Chaf

fey

Peel

at

Para

dis

e W

eir

Peel

at

Apple

by

Cro

ss

Peel

at

Car

roll

Gap

Cock

burn

at

Mulla

Gnoo G

noo a

t M

eadow

s Ln

Man

illa

at G

len R

iddle

Man

illa

d/s

Split

Rock

Mac

donal

d a

t Ben

dem

eer

Nam

oi at

Man

illa

Wei

r

Nam

oi at

Man

illa

Rw

y Br

Nam

oi at

Kee

pit

200

400

600

800

1000

1200

1400

Ele

ctrica

l Conduct

ivity

(µS/c

m)

Median 25%-75% 10%-90%

n 33 37 60 58 60 56 17 47 48 60 60 60 56

The solid line is the ANZECC and ARMCANZ (2000b) default trigger value for the protection of aquatic ecosystems in lowland streams (350 µS/cm). The broken line is the minimum value of the low salinity range for irrigation water (650 µS/cm).



Figure 3: Box plots of electrical conductivity (µS/cm) readings in the lower Namoi Catchment from July 2002 to June 2007

Mooki

at

Bre

eza

Mooki

at

Ruvi

gne

Coxs

at

Tam

bar

Springs

Coxs

at

Boggab

ri

Nam

oi at

Gunned

ah

Mau

les

at A

voca

Eas

t

Nar

rabri a

t N

arra

bri

Nam

oi at

Molle

e

Nam

oi d/s

Gunid

ger

a

Pian

at

Ross

more

Pian

at

Wam

inda

Nam

oi at

Bugilb

one

Nam

oi at

Goan

gra

Nam

oi at

Wal

get

t

400

800

1200

1600

2000

2400

2800

Ele

ctrica

l Conduct

ivity

(µS/c

m)

Median 25%-75% 10%-90%

n 53 31 48 39 60 44 60 60 57 32 39 53 50 55

The solid line is the ANZECC and ARMCANZ (2000b) default trigger value for the protection of aquatic ecosystems in lowland streams (300 µS/cm). The broken line is minimum value of the low salinity range for irrigation water (650 µS/cm)

Figure 4: Comparison of 2002-2007 electrical conductivity (µS/cm) readings in the upper Namoi Catchment with 1990-2000 historical data

Peel

at

Bow

l Alle

y Pt

Peel

d/s

Chaf

fey

Peel

at

Para

dis

e W

eir

Peel

at

Apple

by

Cro

ss

Peel

at

Car

roll

Gap

Man

illa

at G

len R

iddle

Man

illa

d/s

Split

Rock

Nam

oi at

Man

illa

Rw

y Br

Nam

oi at

Kee

pit

200

400

600

800

1000

1200

Ele

ctrica

l Conduct

ivity

(µS/c

m)

Historical data NWQP data

n 93 33 139 37 140 60 165 58 65 60 21 47 29 48 54 60 38 56



Figure 5: Comparison of 2002-2007 electrical conductivity (µS/cm) readings in the lower Namoi Catchment with 1990-2000 historical data

Mooki

at

Bre

eza

Mooki

at

Ruvi

gne

Coxs

at

Tam

bar

Springs

Coxs

at

Boggab

ri

Nam

oi at

Gunned

ah

Nar

rabri a

t N

arra

bri

Nam

oi at

Molle

e

Pian

at

Ross

more

Pia

n a

t W

amin

da

Nam

oi at

Bugilb

one

Nam

oi at

Goan

gra

Nam

oi at

Wal

get

t

200400600800

1000120014001600180020002200240026002800

Ele

ctrica

l Conduct

ivity

(µS/c

m)


n 65 53 19 31 26 48 125 39 254 60 109 60 88 60 154 32 62 39 202 53 66 50 165 55

3.3 Continuous electrical conductivity monitoring

Salt loads are calculated to estimate the amount of salt being washed from the landscape and transported by the river system. Salt loads are calculated using continuous flow and electrical conductivity data collected by Office of Water gauging stations from several sites in the Namoi

Catchment, including:

• Goonoo Goonoo Creek at Meadows Lane;

• Peel River at Paradise Weir;

• Mooki River at Ruvigne;

• Coxs Creek at Boggabri;

• Namoi River at Gunnedah;

• Narrabri Creek at Narrabri, and

• Namoi River at Goangra.

The variability in electrical conductivity through time and the inverse relationship between electrical conductivity and flow in Narrabri Creek at Narrabri is illustrated in Figure 6. Electrical conductivity

readings ranged between 89 µS/cm following minor flooding in July 2005 and 929 µS/cm in October 2003 after an extended period of low flow. The initial stage of a flood is characterised by high electrical conductivity, often called a first flush. These appear as sharp spikes in the data followed by a rapid

decline (Figure 7). As rainfall first starts to run off the landscape, it mobilises salts concentrated on the soil surface and washes them into the waterways. As flow increases, salts concentrated in the bottom of pools are also flushed out. Following this peak, electrical conductivity drops rapidly due to the

dilution of salts by rainwater. The irrigation industry is more likely to experience difficulties with these



high salinity spikes before impacts of any long term accumulation are realised. It would be advisable for irrigators to let this first flush pass downstream before commencing to pump.

Figure 6: Time series plot of flow (ML/day) and electrical conductivity (µS/cm) for Narrabri Creek at Narrabri (419003) from July 2002 to July 2007

July 02Jan 03

July 03Jan 04

July 04Jan 05

July 05Jan 06

July 06Jan 07

July 07

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

Flow

(M

L/day

)

100

200

300

400

500

600

700

800

900

1000

Ele

ctrica

l Conduct

ivity

(µS/c

m)

Flow Electrical conductivity

Blue line is flow (left axis) and red line is electrical conductivity (right axis)

Figure 7: Time series plot of flow (ML/day) and electrical conductivity (µS/cm) for Narrabri Creek at Narrabri (419003) for December 2004

9-Dec-04 11-Dec-04 13-Dec-04 15-Dec-04 17-Dec-04

Date

0

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)

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ctrica

l co

nduct

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(µS/c

m)

Flow Electrical conductivity



The NSW Salinity Strategy (DLWC, 2000) set an end-of valley 2010 electrical conductivity target for the Namoi River at Goangra of 550 µS/cm, which should not be exceeded more than 50% of the time.

An additional target of 1000 µS/cm should not be exceeded more than 20% of the time. These targets

were incorporated into the Murray-Darling Basin Salinity Management Strategy 2001-2015 (2001) which aims to ensure that salinity at Morgan in South Australia should be less than 800 µS/cm, 95% of the time. These targets were also adopted by the Namoi Catchment Management Authority (CMA) as

surface and groundwater management targets in their Catchment Action Plan (2007). Both of the end of valley targets were achieved, with the 1000 µS/cm value only being exceeded on a total of 16 days (4% of the time) over the five year period (Table 4). In contrast, electrical conductivity exceeded the

ANZECC and ARMCANZ (2000b) default protection of aquatic environment in lowland rivers trigger value of 300 µS/cm for approximately 80% of the sampling period (Table 4).

The NSW Salinity Strategy also set a corresponding end of valley 2010 load target for the Namoi River

at Goangra of 79 000 tonnes of salt per annum. The low salt loads in most years (Figure 8) were due to flows throughout the catchment being substantially reduced by continuing drought conditions. The 2004-2005 salt load of 39 000 tonnes was the highest during the sampling period. Almost

31 700 tonnes of this was transported in December 2004 as a result of flooding in the mid and lower catchment. This emphasises the role flooding plays in salt load transport in rivers and streams in the Namoi Catchment.

Figure 8: Cumulative monthly salt loads for the Namoi River at Goangra

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

2002-2003 2003-2004 2004-2005 2005-2006 2006-2007

Salt

Load

s (t

on

nes)

JuneMayAprilMarchFebruaryJanuaryDecemberNovemberOctoberSeptemberAugustJuly

Based on mean daily electrical conductivity and flow data




Table 4: Number and percentage of days where electrical conductivity exceeded Namoi end of valley salinity targets and water quality guidelines (Namoi River at Goangra)

Year No. of days

when data were available

Default trigger value (lowland)

300 µS/cm 1

Namoi end of valley salinity

target <550 µS/cm 50%

of the time 2

Low salinity for

irrigation 650 µS/cm 3

Namoi end of valley salinity

target <1000 µS/cm

80% of the time 2

2002-2003 365 284 (78%) 152 (42%) 48 (13%) 0 (0%)

2003-2004 363 263 (72%) 59 (16%) 52 (14%) 16 (4%)

2004-2005 277 224 (81%) 64 (23%) 14 (5%) 0 (0%)

2005-2006 363 310 (85%) 19 (5%) 0 (0%) 0 (0%)

2006-2007 141 115 (82%) 14 (10%) 0 (0%) 0 (0%)

Based on mean daily electrical conductivity. Percentages calculated using number of days that there was sufficient water at the site to take readings

1. ANZECC and ARMCANZ (2000b) default protection of aquatic environment trigger value for lowland rivers

2. NSW Salinity Strategy (2000) and Namoi CMA Catchment Action Plan (2007) river salinity management target

3. ANZECC and ARMCANZ (2000b) irrigation water guidelines

3.4 Major ions

Many inorganic elements occur naturally in the environment, some of which are required by plants and animals for healthy growth. The major ions that predominate in surface fresh waters are sodium (Na+),

calcium (Ca2+), potassium (K+), magnesium (Mg2+), bicarbonate (HCO3-), sulphate (SO4

2-) and chloride (Cl-). The concentrations and relative proportions of these ions are influenced by catchment geology, land use and rainfall regime. If the concentrations of these substances increase, some can

become highly toxic. Some irrigated crops are sensitive to excessive concentrations of particular ions such as chloride; whilst sodium can damage soil structure and calcium can contribute to water hardness and scaling. Increased proportions of alkaline earth bicarbonates generally indicate

geological influences on water quality, while sodium and chloride usually indicate marine influences.

There was no dominant cation found in the selected sites as demonstrated by central clustering in the bottom left hand triangle (Figure 9), though there was some minor variability between sites. The Mooki

River at Ruvigne had higher concentrations of sodium and magnesium in some samples. Bicarbonate is the dominant anion at most sites (samples clustered in the corner of the bottom right hand triangle), with some samples from the Mooki River at Ruvigne being dominated by chloride salts. These

samples dominated by chloride salts were collected during periods when the Mooki River was flowing. This raises concerns for irrigators extracting water in the lower Mooki Catchment where the median conductivity readings are above the low salinity guideline for irrigation water with a dominance of

sodium and chloride salts.


Figure 9: Piper diagram of major ions data from selected sites in the Namoi Catchment

Narrabri at Narrabri

Namoi at Goangra

Coxs at Boggabri

Mooki at Ruvigne

Ca

SO 4 Mg HCO 3 +CO 3 Na + K

Cl

100 80

0

60 40

20

100 80

0

60 40

20

0 20

100

40 60

80

100 80

0

60 40

20

100 80 0 60 40 20 0 20 100 40 60 80

0 20

100

40 60

80

100 80

0

60 40

20

Cl + SO 4

0 20

100

40 60

80

0 20

100

40

60 80

Ca + Mg

Cations Anions

Piper diagrams consist of two triangles (one for cations and one for anions) and a central diamond shaped figure. The cations (calcium, magnesium and sodium) are plotted on the bottom left triangle, and anions (bicarbonate, sulphate and chloride) are plotted on the bottom right triangle. Both are percentages based on concentrations in milliequivalents per litre (meq/L). Points on the anion and cation diagrams are then projected upward to where they intersect on the diamond.



3.5 Turbidity

Turbidity is a measure of the clarity of the water using light scattering within the water. High turbidity is caused by suspended sediment, including fine silt, clay particles or organic material. 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 amounts of suspended

sediments have varied effects, the most obvious being the water appears muddy. 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 our river systems, attached to

suspended sediments. Turbidity is measured in Nephelometric Turbidity Units (NTU).

The bulk of sediment in the Namoi River is derived from sub-soil sources, indicating that gully and channel bank erosion processes produce most of the sediment (Caitcheon et al., 1999). Low flows

during the study period would have minimised these erosion processes, assisting in maintaining lower turbidity levels. The Peel River at Appleby Crossing and Carroll Gap were the only two sites in the upper catchment where the majority of samples exceeded the ANZECC and ARMCANZ (2000b)

default trigger value of 25 NTU (Figure 10). There is a marked difference between the Namoi River at Manilla Railway Bridge, located upstream of Keepit Dam, and Namoi River at Keepit, located below the dam, with the downstream site eliciting lower levels. The three major storages in the Namoi

Catchment are considered to trap most of the sediment derived from the upland areas (Caitcheon et al., 1999).

There is a general trend toward increasing turbidity with distance down the catchment as cumulative

impacts increase (Figure 11). The majority of sites had similar turbidity levels to the previous ten year data set (Figures 12 and 13). Coxs Creek at Boggabri may have been impacted by the livestock observed at the sampling site during the extended dry periods, resulting in the higher turbidity during

the NWQP.



Figure 10: Box plots of turbidity (NTU) readings in the upper Namoi Catchment from July 2002 to June 2007

Peel

at

Bow

l Alle

y Pt

Peel

d/s

Chaf

fey

Peel

at

Para

dis

e W

eir

Peel

at

Apple

by

Cro

ss

Peel

at

Car

roll

Gap

Cock

burn

at

Mulla

Gnoo G

noo a

t M

eadow

s Ln

Man

illa

at G

len R

iddle

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illa

d/s

Split

Rock

Mac

donal

d a

t Ben

dem

eer

Nam

oi at

Man

illa

Wei

r

Nam

oi at

Man

illa

Rw

y Br

Nam

oi at

Kee

pit

10

20

30

40

50

60

70

Turb

idity

(NTU

)

Median 25%-75% 10%-90%

n 34 38 60 58 60 56 17 58 59 60 60 60 56

The black line is the ANZECC and ARMCANZ (2000) default trigger value for the protection of aquatic ecosystems in upland streams (25 NTU)

Figure 11: Box plots of turbidity (NTU) readings in the lower Namoi Catchment from July 2002 to June 2007

Mooki

at

Bre

eza

Mooki

at

Ruvi

gne

Coxs

at

Tam

bar

Springs

Coxs

at

Boggab

ri

Nam

oi at

Gunned

ah

Mau

les

at A

voca

Eas

t

Nar

rabri a

t N

arra

bri

Nam

oi at

Molle

e

Nam

oi d/s

Gunid

ger

a

Pian

at

Ross

more

Pia

n a

t W

amin

da

Nam

oi at

Bugilb

one

Nam

oi at

Goan

gra

Nam

oi at

Wal

get

t

50

100

150

200

250

300

350

400

Turb

idity

(NTU

)

Median 25%-75% 10%-90%

n 53 31 48 39 60 44 60 60 57 32 39 53 50 55

The black line is the ANZECC and ARMCANZ (2000) default trigger value for the protection of aquatic ecosystems in lowland streams (50 NTU)



Figure 12: Comparison of 2002-2007 turbidity (NTU) readings in the upper Namoi Catchment with 1990-2000 historical data

Pee

l at

Bow

l Alle

y P

t

Pee

l d/s

Cha

ffey

Pee

l at

Par

adis

e W

eir

Pee

l at

App

leby

Cro

ss

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l at

Car

roll

Gap

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illa

at G

len

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dle

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illa

d/s

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it R

ock

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t M

anill

a R

wy

Br

Nam

oi a

t K

eepi

t0

10

20

30

40

50

60

70

80

90

Turb

idity

(NTU

)


n 262 34 164 38 142 60 164 58 68 60 51 58 59 59 56 60 72 56

Figure 13: Comparison of 2002-2007 turbidity (NTU) readings in the lower Namoi Catchment with 1990-2000 historical data

Mooki

at

Bre

eza

Mooki

at

Ruvi

gne

Coxs

at

Tam

bar

Springs

Coxs

at

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ri

Nam

oi at

Gunned

ah

Nar

rabri a

t N

arra

bri

Nam

oi at

Molle

e

Pia

n a

t Ross

more

Pia

n a

t W

amin

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oi at

Bugilb

one

Nam

oi at

Goan

gra

Nam

oi at

Wal

get

t

0

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100

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300

350

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Turb

idity

(NTU

)


n 69 53 20 31 27 48 126 39 261 60 110 60 91 60 110 32 65 39 207 53 72 50 165 55



3.6 Nutrients

Sources of nutrient contamination include sewage treatment works, farm effluent, runoff from agricultural land, septic tanks, industrial effluent and urban storm water runoff. 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). Inputs related to human activity such as fertiliser and manure from livestock were not found by Caitcheon et al. (1999) to be significant contributors in the Namoi Catchment as a whole. The main transport mechanism is the movement of nutrients attached to suspended material. For this reason, where the majority of nutrients are from non point sources (e.g. farm runoff), there is generally a strong

relationship to flow. As flow increases so does the concentration of nutrients. High concentrations of nutrients are important factors in the formation of algal blooms, often referred to as eutrophication. Nutrient levels do not actually trigger an algal bloom, but can sustain a bloom and determine how

large the bloom can become. Other factors such as water temperature, turbidity and water turbulence are also important for bloom formation (Rissik et al., 2009).

3.6.1 Total phosphorus

All sites in the Namoi Catchment had median total phosphorus concentrations above the ANZECC

and ARMCANZ (2000b) trigger values (Figures 14 and 15), meaning there was ample phosphorus present in the river systems to encourage algae growth. Blooms of potentially toxic blue-green algae were detected in the Namoi River at Gunnedah, Mollee Weir, Gunidgera Weir, Bugilbone and Walgett

at various times throughout the project, but not to the extent suggested as possible by the total phosphorus results. This indicates that other factors such as turbidity, flow and water temperature may not have been favourable for sustained algal growth.

The highest median concentration of phosphorus in the upper catchment was in the Peel River at Appleby Crossing. This site is located downstream of Tamworth and is influenced by the sewage treatment plant and urban runoff. Due to the dry conditions there was very little natural flow in the Peel

River to dilute the nutrient rich water being released from the plant. Research by Caitcheon et al. (1999) on discharges from the Narrabri sewage treatment plant into the Namoi River found a significant local effect on total phosphorus concentrations. However, with distance downstream, the

phosphorus was assimilated by the river, possibly through phytoplankton uptake and deposition, uptake by benthic organisms or by adsorption onto the sediment of the river bed (Caitcheon et al., 1999). These processes may account for the drop in phosphorus concentrations in the Peel River

between the Appleby Crossing and Carroll Gap sites (Figure 14).

The Mooki River at Ruvigne and Coxs Creek at Boggabri also had high phosphorus concentrations. The alluvial soils in these two catchments are naturally high in phosphorus (Banks, 1995) and as

these soils are eroded into the river system, the associated phosphorus is also transported downstream.

In most cases phosphorus concentrations were similar to or slightly lower than the 1990-2000 ten year

data set (Figures 16 and 17) due to low flows and drought reducing the mobilisation of phosphorus from the catchment. The higher median in the Mooki River at Ruvigne could be a local issue attributed to livestock having access to the sampling site during the drought (input of phosphorus from faeces

and cattle pugging the bed and banks and stirring up sediments) as well as the concentration of nutrients as water levels decreased.



Figure 14: Box plots of total phosphorus (mg/L) readings in the upper Namoi Catchment from July 2002 to June 2007

Peel

at

Bow

l Alle

y Pt

Peel

d/s

Chaf

fey

Peel

at

Para

dis

e W

eir

Peel

at

Apple

by

Cro

ss

Peel

at

Car

roll

Gap

Cock

burn

at

Mulla

Gnoo G

noo a

t M

eadow

s Ln

Man

illa

at G

len R

iddle

Man

illa

d/s

Split

Rock

Mac

donal

d a

t Ben

dem

eer

Nam

oi at

Man

illa

Wei

r

Nam

oi at

Man

illa

Rw

y Br

Nam

oi at

Kee

pit

0.1

0.2

0.30.7

0.81.0

1.1

1.2

Tota

l Ph

osp

horu

s (m

g/L

)

Median 25%-75% 10%-90%

n 34 38 60 58 60 56 17 59 58 60 60 60 56

The black line is the ANZECC and ARMCANZ (2000b) default trigger value for the protection of aquatic ecosystems in upland streams (0.02 mg/L). Note scale breaks to maintain emphasis on core data.

Figure 15: Box plots of total phosphorus (mg/L) readings in the lower Namoi Catchment from July 2002 to June 2007

Mooki

at

Bre

eza

Mooki

at

Ruvi

gne

Coxs

at

Tam

bar

Springs

Coxs

at

Boggab

ri

Nam

oi at

Gunned

ah

Mau

les

at A

voca

Eas

t

Nar

rabri a

t N

arra

bri

Nam

oi at

Molle

e

Nam

oi d/s

Gunid

ger

a

Pia

n a

t Ross

more

Pia

n a

t W

amin

da

Nam

oi at

Bugilb

one

Nam

oi at

Goan

gra

Nam

oi at

Wal

get

t

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Tota

l Ph

osp

horu

s (m

g/L

) Median 25%-75% 10%-90%

n 53 31 48 39 60 44 60 60 56 32 39 53 50 55

The black line is the ANZECC and ARMCANZ (2000b) default trigger value for the protection of aquatic ecosystems in lowland streams (0.05 mg/L)



Figure 16: Comparison of 2002-2007 total phosphorus (mg/L) readings in the upper Namoi Catchment with 1990-2000 historical data

Pee

l at

Bow

l Alle

y Pt

Peel

d/s

Chaf

fey

Pee

l at

Par

adis

e W

eir

Pee

l at

Apple

by

Cro

ss

Pee

l at

Car

roll

Gap

Man

illa

at G

len R

iddle

Man

illa

d/s

Split

Rock

Nam

oi at

Man

illa

Rw

y Br

Nam

oi at

Kee

pit

0.0

0.1

0.2

0.3

0.4

0.50.70.81.0

1.1

1.2

Tota

l Phosp

horu

s (m

g/L

)


n 266 34 157 38 145 60 169 58 62 60 52 59 53 58 50 60 63 56

Note scale breaks to maintain emphasis on core data.

Figure 17: Comparison of 2002-2007 total phosphorus (mg/L) readings in the lower Namoi Catchment with 1990-2000 historical data

Mooki

at

Bre

eza

Mooki

at

Ruvi

gne

Coxs

at

Tam

bar

Springs

Coxs

at

Boggab

ri

Nam

oi at

Gunned

ah

Nar

rabri a

t N

arra

bri

Nam

oi at

Molle

e

Pian

at

Ross

more

Pian

at

Wam

inda

Nam

oi at

Bugilb

one

Nam

oi at

Goan

gra

Nam

oi at

Wal

get

t

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Tota

l Ph

osp

horu

s (m

g/L

)


n 68 53 20 31 22 48 121 39 258 60 106 60 84 60 110 32 65 39 211 53 66 50 164 55



3.6.2 Total nitrogen

Sites with high concentrations of phosphorus, such as Peel at Appleby Crossing, Mooki River at Breeza and Ruvigne, Coxs Creek at Boggabri and Pian Creek at Waminda, also had the highest median nitrogen concentrations (Figures 18 and 19). As nitrogen and phosphorus often originate and

are transported via similar mechanisms (i.e. attached to soil or organic particles), relative concentration levels between the two nutrients are usually similar. If sediment is prevented from entering the river system by reducing erosion and by managing riparian vegetation, levels of both

these nutrients can be reduced.

A substantial drop in nitrogen concentrations in the Peel River between Appleby Crossing and Carroll Gap can be observed in Figure 18. In similar processes to phosphorus, it may be that nitrogen is being

absorbed onto soil particles in the water column and bed sediments and taken up by benthic and filamentous algae and aquatic plants growing in the river or denitrified by bacteria.

As for phosphorus, the Mooki River at Ruvigne and Coxs Creek at Boggabri had higher median

nitrogen levels than the previous ten year median (Figure 21). Most other sites had nitrogen levels similar to or lower than historical data.

Figure 18: Box plots of total nitrogen (mg/L) readings in the upper Namoi Catchment from July 2002 to June 2007

Peel

at

Bow

l Alle

y Pt

Peel

d/s

Chaf

fey

Peel

at

Para

dis

e W

eir

Peel

at

Apple

by

Cro

ss

Peel

at

Car

roll

Gap

Cock

burn

at

Mulla

Gnoo G

noo a

t M

eadow

s Ln

Man

illa

at G

len R

iddle

Man

illa

d/s

Split

Rock

Mac

donal

d a

t Ben

dem

eer

Nam

oi at

Man

illa

Wei

r

Nam

oi at

Man

illa

Rw

y Br

Nam

oi at

Kee

pit

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Tota

l N

itro

gen

(m

g/L

) Median 25%-75% 10%-90%

n 34 38 60 58 60 56 16 58 59 60 60 60 56

The black line is the ANZECC and ARMCANZ (2000b) trigger value for the protection of aquatic ecosystems in upland streams (0.2 mg/L)



Figure 19: Box plots of total nitrogen (mg/L)) readings in the lower Namoi Catchment from July 2002 to June 2007

Mooki

at

Bre

eza

Mooki

at

Ruvi

gne

Coxs

at

Tam

bar

Springs

Coxs

at

Boggab

ri

Nam

oi at

Gunned

ah

Mau

les

at A

voca

Eas

t

Nar

rabri a

t N

arra

bri

Nam

oi at

Molle

e

Nam

oi d/s

Gunid

ger

a

Pia

n a

t Ross

more

Pia

n a

t W

amin

da

Nam

oi at

Bugilb

one

Nam

oi at

Goan

gra

Nam

oi at

Wal

get

t

1

2

3

4

5

Tota

l N

itro

gen

(m

g/L

)

Median 25%-75% 10%-90%

n 53 31 48 39 60 44 60 59 56 32 39 53 50 55

The black line is the ANZECC and ARMCANZ (2000b) trigger value for the protection of aquatic ecosystems in lowland streams (0.6 mg/L)

Figure 20: Comparison of 2002-2007 total nitrogen (mg/L) readings in the upper Namoi Catchment with 1990-2000 historical data

Peel

at

Bow

l Alle

y Pt

Peel

d/s

Chaf

fey

Peel

at

Para

dis

e W

eir

Peel

at

Apple

by

Cro

ss

Man

illa

at G

len R

iddle

Man

illa

d/s

Split

Rock

Nam

oi at

Kee

pit

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Tota

l N

itro

gen

(m

g/L

) Historical data NWQP data

n 206 34 49 38 144 60 169 58 52 58 47 59 51 56



Figure 21: Comparison of 2002-2007 total nitrogen (mg/L) readings in the lower Namoi Catchment with 1990-2000 historical data

Mooki

at

Ruvi

gne

Coxs

at

Tam

bar

Springs

Coxs

at

Boggab

ri

Nam

oi at

Gunned

ah

Nar

rabri a

t N

arra

bri

Nam

oi at

Molle

e

Pia

n a

t Ross

more

Nam

oi at

Bugilb

one

Nam

oi at

Wal

get

t

1

2

3

4

5

Tota

l N

itro

gen

(m

g/L

)


n 20 31 20 48 96 39 200 60 106 60 42 59 106 32 203 53 159 55

3.7 Pesticides

Agricultural systems are increasingly reliant on chemical use to control weeds and insect pests. This reliance on chemicals has resulted in fears within the community, particularly related to human health

issues and the build-up of pesticides in soil and water. The detection of pesticide residues (including insecticides and herbicides) in river water is of great concern to water managers and the community as a whole as the effects of long term, low dose (chronic) exposure to pesticides on humans and the

environment are largely unknown. Spray drift, vapour transport and runoff are the main pathways for pesticide transport into river systems (Mawhinney, 1998a; Raupach et al., 2001).

The routine monitoring of agricultural chemicals in the waterways of the Namoi Catchment

commenced in late 1991 under the Central and Northwest Regions Water Quality Project. This data, collected between 1991 and 2002, has been included in Figures 22 and 23 and Table 5 as a comparison to the more recent NWQP results. The data represented in this report includes sites

located downstream of Keepit Dam which encompasses the majority of dryland and irrigated cropping areas of the Namoi Valley.

For the NWQP, samples were analysed for a total of 43 agricultural chemicals. In this report the term

pesticide includes insecticides, herbicides and defoliants. The list of pesticides (Appendix 3) includes the alpha and beta isomers of endosulfan, as well as endosulfan sulfate. The breakdown products of atrazine; desethyl atrazine and hydroxy atrazine have also been included. In this report, atrazine

concentrations refer to the sum of atrazine and two of the breakdown products desethyl atrazine and hydroxy atrazine. Similarly total endosulfan concentration is the sum of alpha and beta endosulfan and endosulfan sulphate.



3.7.1 Insecticides

3.7.1.1 Endosulfan

Endosulfan is an organochlorine insecticide, used to control sucking, chewing, and boring insects and

mites in a range of crops, including cotton and sorghum. The Central and North West Regions Water Quality Program found endosulfan to be the most commonly detected insecticide in rivers in this area (Muschal, 2001). Since the commencement of the NWQP in 2002, endosulfan sulphate was only

detected on a total of eight occasions in the Namoi Catchment. Residue concentrations ranged from 0.01 to 0.02 µg/L. The Australian and New Zealand trigger value for 99% ecosystem protection for endosulfan is 0.03 µg/L (ANZECC and ARMCANZ, 2000b). The 99% ecosystem protection level

means that 99% of species are expected to be protected if concentrations remain below the trigger value. Endosulfan residues were detected in the Namoi River between Wee Waa and Walgett and in Pian Creek in January and February 2005, coinciding with the end of the spraying period for

endosulfan (spraying ends 15th January), and flooding in the mid to lower catchment in December 2004. The chemical present was the breakdown product endosulfan sulphate rather than the parent isomers (alpha and beta), which suggests the chemical was transported in runoff rather than via direct

spray drift.

Endosulfan monitoring data from 1991 to 2007 (Figure 22 and Table 5) illustrates a rapid decline in the detection of endosulfan residues from the 1997-1998 to the 1999-2000 cotton growing seasons. Prior

to 1998-1999, between 44% and 67% of samples contained endosulfan residues, many exceeding the Australian and New Zealand water quality guideline trigger value for 99% ecosystem protection (ANZECC and ARMCANZ, 2000b). Numerous factors such as the development and implementation of

the Best Management Practices Manual by the Australian Cotton Industry in 1997, the detection of endosulfan residues in cattle in 1998-1999 resulting in the introduction of restrictions on endosulfan use, improved tail water return systems, the introduction of Bt cotton (Inguard introduced in 1996 and

Bollguard II in 2002) contributing to the significant reduction in the use of pesticides (Doyle et al., 2002), integrated pest management and continued education regarding industry best practice have all helped reduce the movement of this chemical into river systems.




Figure 22: Box plot of total endosulfan concentrations in pesticide samples collected downstream of Keepit Dam from 1991-1992 to 2006-2007

1991-9

2

1992-9

3

1993-9

4

1994-9

5

1995-9

6

1996-9

7

1997-9

8

1998-9

9

1999-0

0

2000-0

1

2001-0

2

2002-0

3

2003-0

4

2004-0

5

2005-0

6

2006-0

7

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

Tota

l Endosu

lfan

(µg/L

)

Median 25%-75% 10%-90%

n 95 78 66 63 64 152 153 162 172 160 94 101 101 103 105 62

The broken line represents the ANZECC and ARMCANZ (2000b) water quality trigger value for 99% ecosystem protection

r

te 2005.

10-4µg/L and 0.1µg/L respectively. There are no ecosystem rofenofos.

e

(0.03 µg/L)

3.7.1.2 Other insecticides

Three additional insecticides were detected once during the NWQP; chlorpyrifos, dimethoate and profenofos. Chlorpyrifos is a non-systemic insecticide used to control a range of insects in soil o

foliage in a range of crops. It was detected once in Narrabri Creek at Narrabri in May 2004 at a concentration of 0.8 µg/L. Residue of profenofos (0.06 µg/L) was detected in the Namoi River at Bugilbone in February 2005. These two organophosphate insecticides have a high potential for

causing harm to animals in the aquatic ecosystem (Muschal, 2003). Dimethoate is used to control a variety of insects on various crops. Its principal use is for the control of thrips and mites on cotton, lain the growing season. The Mooki River at Ruvigne had a concentration of 0.05 µg/L in April

The ANZECC and ARMCANZ (2000b) trigger value for 99% ecosystem protection level for chlorpyrifos and dimethoate are 0.4x protection guidelines for p

3.7.2 Herbicides

3.7.2.1 Atrazine

The herbicide atrazine continues to be detected regularly in the Namoi Catchment, with residues of

the active ingredient and/or one of the breakdown products (hydroxy atrazine and desethyl atrazine) being detected at all sites monitored for pesticide residues at some stage during the project. Atrazinis a selective herbicide from the triazine group and is used as a residual chemical for pre and post



emergence control of annual grasses and broad leaf weeds in summer crops, principally in sorghum. Most atrazine residues remain distributed in the upper layers of cropping soils (Hargreaves and Noble, 1993), though it is not strongly adsorbed onto clay particles or organic matter leaving it prone to being

transported into waterways by stormwater runoff. Studies have also shown atrazine to be one of the

.

e

ow

reduced atrazine applied and low surface runoff to

transport chemical residues into the river system.

Figure 23 tions in pesticide samples collected downstream of Keepit Dam from 1991-1992 to 2006-20007

most widely detected agricultural chemicals in surface waters of north-western NSW (Muschal, 2001)

Residues of atrazine, or a breakdown product, were detected on a total of 257 occasions during th

NWQP, which comprises almost 55% of the pesticide samples collected over the five year period between 2002 and 2007. The results ranged from 0.05 to 8.6 µg/L. The ANZECC and ARMCANZ (2000b) trigger value for 99% ecosystem protection for atrazine is 0.7 µg/L. This trigger value was

exceeded on three occasions. The highest 20 results were from waterways on the Liverpool Plains.

Comparing the NWQP atrazine data with previous monitoring programs (Figure 23 and Table 5) shthe detection of atrazine residues in the Namoi Catchment fluctuates through time. Relatively low

concentrations and rates of detection appear to be observed during dry years such as 2001-2002 and 2002-2003, rather than as a consequence of changes to land management. The drought conditions result in a reduced area of summer crops planted,

: Box plot of total atrazine concentra

1991-9

2

1992-9

3

1993-9

4

1994-9

5

1995-9

6

1996-9

7

1997-9

8

1998-9

9

1999-0

0

2000-0

1

2001-0

2

2002-0

3

2003-0

4

2004-0

5

2005-0

6

2006-0

7

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Tota

l Atr

azin

e (µ

g/L

)

Median 25%-75% 10%-90%

n 95 78 66 63 64 152 153 162 172 160 94 101 101 103 105 62

The broken line represents the ANZECC and ARMCANZ (2000b) water quality trigger value for 99% ecosystem protection

.7 µg/L)

(0


3.7.2.2 Other herbicides

The residues of other herbicides detected during the NWQP include metolachlor, diuron, fluometuron,

prometryn, simazine, pendimethalin, MCPA and 2,4-D.

Metolachlor is used for the pre plant and pre emergence control of annual grasses and some broad leaf weeds in a range of crops including cotton, sorghum and sunflowers. Due to its high water

solubility it can be detected in groundwater, and is prone to transport by runoff. Metolachlor was detected at all sites analysed for pesticides during the project. Concentrations ranged from 0.05 to 18.6 µg/L, with the majority of detections in Coxs Creek at Boggabri and the Mooki River at Ruvigne.

Fluometuron was detected on 27 occasions, most commonly in the Mooki at Ruvigne, Coxs Creek at Boggabri and Namoi River at Walgett. Concentrations ranged between 0.1 and 1.6 µg/L. This herbicide is used for pre and post emergence control of annual broad leaf weeds and grasses in

cotton. Fluometuron has a high water solubility which leaves it open to being washed into surface water by runoff.

Prometryn is a triazine herbicide used as a pre or post emergence control of most annual grasses and

broad leaf weeds in cotton. It is sprayed in early growth stages to avoid foliar injury. It was detected on 18 occasions, eight of which were in the Mooki River at Ruvigne. Concentrations across the catchment ranged from 0.05 to 0.95 µg/L.

Diuron is used for selective control of germinating grasses and broad leaf weeds in summer crops, and total control of most weeds on non-crop areas when used at high rates. As diuron is strongly bound to clay particles and organic matter, the possibility of it entering surface water via runoff and

erosion is high. Residues were detected at seven sites on a total of 11 occasions at concentrations ranging from 0.1 to 0.8 µg/L.

2,4-D controls broad leaf weeds in cultivation areas. It was detected on 12 occasions, principally in the

upper cropping areas at Coxs Creek at Boggabri, Mooki River at Ruvigne and the Namoi River at Gunnedah. Concentrations ranged from 0.2 to 1.0 µg/L. The ANZECC and ARMCANZ (2000b) trigger value for 2,4-D is 140 µg/L.

MCPA is a post emergence herbicide used to control annual and perennial weeds in cereals. Similar to 2,4-D, it was detected in the upper cropping areas at concentrations ranging from 0.3 to 2.0 µg/L.

Simazine was detected on four occasions in Coxs Creek at Boggabri and once each in the Namoi

River at Gunidgera Weir, Bugilbone, Goangra and Walgett. Results ranged from 0.05 to 0.2 µg/L. Simazine is used for the control of most germinating grasses and broad leaf weeds. The ANZECC and ARMCANZ (2000b) trigger value for simazine is 0.2 µg/L.

Pendimethalin is used for the control of most annual grasses and many annual broad leaf weeds in summer crops, principally sunflowers. It was detected once in the Mooki River at Ruvigne. It is strongly adsorbed to upper soil layers, which suggests it is most commonly transported off farm by

storm runoff, but may not be readily mobilised otherwise.

Similar to endosulfan, there has been a marked decline in the detections of herbicides such as diuron, fluometuron, metolachlor and prometryn since the 2000-2001 season (Table 5). This could be a

consequence of the dryer conditions, in conjunction with the introduction of Roundup Ready® cotton varieties in 2001-2002, seeing cotton growers become more reliant on glyphosate for weed control. Pesticide samples were not analysed for residues of glyphosate, as its rapid breakdown time means it

would rarely be detected.

The long term impact of constant exposure to herbicides on the riverine environment is not clearly understood. The persistent, low background level, which at some sites is present all year round (i.e.

Mooki River at Ruvigne and Coxs Creek at Boggabri) needs to be addressed in dryland cropping areas. In some cases the residues of up to five different herbicides were present in the one sample.



This raises the concern of not only long term exposure of ecosystems to herbicides, but also the additive impact or interaction of combinations of herbicides on aquatic ecosystems, which is also poorly understood.

The continued detection of agricultural chemical residues shows a need for a concerted effort by all farmers, agricultural chemical suppliers and sprayers to follow the guidelines for the handling, storage and application of pesticides and to keep up to date with weather forecasts to avoid spraying before

heavy rainfall. To further reduce the amounts of chemicals in surface water, extra care must be taken when spraying near sensitive areas, such as close to creeks and rivers. In addition, filters such as grassed waterways, natural grasslands or vegetated buffer strips can reduce pollutant concentrations

in runoff (Rattray et al., 2006).

Table 5: Number and percentage of detections of common pesticides in the Namoi Catchment from 1991-1992 through to 2006-2007

Year n Endosulfan Atrazine Diuron Fluometuron Metolachlor Prometryn

1991-92 95 42 (44% ) 51 (54%) 11 (12%) 2 (2.1%) 0 10 (11%)

1992-93 78 46 (59% ) 24 (31%) 4 (5.1%) 2 (2.6%) 0 3 (3.8%)

1993-94 66 41 (62%) 33 (50%) 3 (4.5%) 5 (7.6%) 10 (15%) 3 (4.5%)

1994-95 63 31 (49%) 21 (33%) 0 0 2 (3.2%) 3 (4.8%)

1995-96 64 43 (67%) 32 (50%) 1 (1.7%) 0 9 (14%) 4 (6.3%)

1996-97 152 71 (47%) 75 (49%) 7 (4.6%) 20 (13%) 15 (9.9%) 12 (7.9%)

1997-98 153 73 (48%) 48 (31%) 10 (6.5%) 39 (25%) 32 (21%) 34 (22%)

1998-99 162 56 (35%) 85 (52%) 16 (9.9%) 22 (14%) 42 (26%) 6 (3.7%)

1999-00 172 16 (9.3%) 90 (52%) 9 (5.3%) 17 (9.9%) 35 (20%) 7 (4.1%)

2000-01 160 12 (7.5%) 89 (56%) 12 (7.5%) 37 (23%) 43 (27%) 6 (3.8%)

2001-02 94 0 13 (14%) 4 (4.3%) 4 (4.3%) 5 (5.3%) 5 (5.3%)

2002-03 101 0 25 (25%) 3 (3.0%) 7 (6.9%) 3 (3.0%) 3 (3.0%)

2003-04 101 0 62 (61%) 3 (3.0%) 6 (5.9%) 11 (11%) 2 (2.0%)

2004-05 103 8 (7.8%) 58 (56%) 1 (1.0%) 4 (3.9%) 27 (26%) 5 (4.9%)

2005-06 105 0 67 (64%) 1 (1.0%) 9 (8.6%) 14 (13%) 8 (7.6%)

2006-07 62 0 45 (73%) 3 (4.8%) 1 (1.6%) 7 (11%) 2 (3.2%)



4. Summary and conclusions

The Namoi River at Goangra contributed total annual salt loads below the NSW Salinity Strategy end

of valley target for the five year period from 2002-2007. This was attributed to low flows in the Namoi River during the sampling period. Routine monthly electrical conductivity results identified the Mooki and Peel Rivers as major contributors of salts to the Namoi River, with releases from Keepit Dam

providing dilution flows. The salinity levels in the lower Namoi Catchment were below the low salinity level for irrigation water (ANZECC and ARMCANZ 2000). This is positive for the irrigation industry in the lower catchment, but water users should avoid pumping during the first flush phase of high flow

events and floods when most of the salts are mobilised.

Turbidity increased with distance down the catchment. Turbidity is only likely to decrease with significant stabilisation of stream bed, banks and gullies throughout the catchment. A reduction in

turbidity levels will take time, as large volumes of sediment are reworked through the system.

Phosphorus and nitrogen concentrations were generally not limiting to algal growth in the Namoi Catchment. High nutrient concentrations combined with the low flows experienced during the sampling

period, provided conditions favourable for the growth of potentially toxic blue-green algae, as they have a competitive advantage over other algal species under these conditions. Results from algal monitoring programs show that high blue-green algae biovolumes did not eventuate in the rivers to the

extent suggested by the high nutrient levels, indicating that other factors such as flow, turbidity and light availability were limiting factors. As for turbidity, riparian vegetation and bed and bank stabilisation is vital for reducing nutrient input. Phosphorus and nitrogen levels in the Peel River

downstream of Tamworth continue to remain high due to the influence of sewage treatment plant outflows and urban runoff.

The insecticide endosulfan was detected in the Namoi Catchment in January 2005 for the first time

since the 2000-2001 cotton growing season. The detection of residues coincided with the peak period for endosulfan use and following minor flooding in the lower catchment. The breakdown product endosulfan sulfate rather than the parent isomers (alpha and beta) was detected, suggesting the

chemical entered the river systems in surface runoff rather than spray drift.

Atrazine, a widely used herbicide, continues to be detected at a variety of sites, with the majority of detections from two sites on the Liverpool Plains; Mooki River at Ruvigne and Coxs Creek at

Boggabri. More work is required to reduce the movement of this herbicide into our waterways, particularly in dryland cropping areas.

Water quality trends were not assessed due to the extremely dry weather conditions experienced

during the project and the insufficient length of datasets required to detect significance. Continued monitoring is required through both wet and dry cycles to allow accurate trend assessment.

Pollutants such as sediment, nutrients and pesticides can be prevented from entering our waterways

through land, soil and vegetation management. Maintaining groundcover, vegetated buffer strips, best management practices for chemical handling and application, minimum/zero tillage and good agronomic practices in conjunction with the management of riparian vegetation to reduce stream bank

erosion provide simple and effective means to improve water quality in the Namoi Catchment.



5. Future water quality monitoring

The Surface Water quality Assessment and Monitoring Project (SWAMP) is a NSW Office of Water

state wide program which commenced in November 2007. This project replaced numerous regionally based water quality programs (such as the Namoi Water Quality Project) and re-established monitoring programs in catchments where they had lapsed.

The objective of the SWAMP is to collect high quality long term water quality data on important catchment and river health indicators at strategic locations from rivers across NSW. These data will be used to meet water resource condition and trend reporting requirements in line with the NSW State

Plan including State of the Environment and State of the Catchment reporting, the Murray Darling Basin Authority (Basin Plan) and the Department of Environment, Water, Heritage and the Arts (National Water Quality Management Strategy).

Numerous sites previously monitored under the NWQP will be continuing to maintain long term datasets. These sites include:

• Namoi River at Gunnedah (419001);

• Narrabri Creek at Narrabri (419003);

• Peel River at Carroll Gap (419006);

• Cockburn River at Mulla Crossing (419016);

• Namoi River at Bugilbone (419021);

• Namoi River at Manilla Railway Bridge (419022);

• Peel River at Paradise Weir (419024);

• Namoi River at Goangra (419026);

• Mooki River at Breeza (419027), and

• Coxs Creek at Boggabri (419032).



6. References ANZECC and ARMCANZ. (2000a). Australian guidelines for water quality monitoring and reporting.

Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand. ISBN 09578245 1 3

ANZECC and ARMCANZ. (2000b). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand.

Banks, R.G. (1995). Soil Landscapes of the Curlewis 1:100 000 Sheet. Department of Conservation and Land Management.

Caitcheon, G.C., Beavis, S.G., Crapper, P., Deitrich, C.R., Green, T.R., Hancock, G., Jakeman, A.J., Olley, J.M., Olley, J.M., Wallbrink, P.J. and Zhang, L. (1999). Sediment and phosphorus sources in the Namoi River Basin. Compiled and edited by Caitcheon GC. CSIRO Land and Water and Australian National University.

Department of Land and Water Conservation. (1999). Namoi Catchment Stressed Rivers Assessment Report. Department of Land and Water Conservation, Sydney. ISBN 0 7347 5081 1

Department of Land and Water Conservation. (2000). Taking on the challenge: NSW Salinity Strategy. Department of Land and Water Conservation, Sydney. ISBN 0 7347 5146 X.

Doyle, B; Reeve, I; and Barclay, E, (2002), The Performance of Ingard Cotton in Australia during the2000/01 Season, Cotton Research and Development Corporation.

Foster, N., Powell, S., Mawhinney, W. and Hohnberg, D. (2000). Riverine condition assessment of the Namoi Catchment. Department of Land and Water Conservation, Tamworth.

Gordon, A. (2001). Central and North West Regions water quality program. 1999-2000 report on nutrients and general water quality monitoring. New South Wales Department of Land and Water Conservation, Parramatta. ISSN 1327-1040

Hargreaves, P.A. and Noble, R.M. (1993). Measurement of herbicide residues in soils from reduced tillage sites. Final Report to Wheat Research Committee for Queensland, WRCQ - 90470, 1990-1992. 10 pp. Department of Primary Industries, Queensland.

Lampert, G. and Short, A. (2004). River Styles®, Indicative geomorphic condition and geomorphic priorities for river conservation and rehabilitation in the Namoi Catchment, Northwest NSW.

Mawhinney, W. (1998a). Liverpool Plains Water Quality Project. Land use, pesticide use and their impact on water quality on the Liverpool Plains. Department of Land and Water Conservation. ISSN 1329-8984

Mawhinney, W. (1998b). Liverpool Plains Water Quality Project. 1996/98 report on nutrients and general water quality monitoring. Department of Land and Water Conservation. ISSN 1329-8984

Mawhinney, W. (2003a). Namoi water quality project operations manual. Internal document. Department of Land and Water Conservation, Tamworth.

Mawhinney, W. (2003b). Point source salinity investigation project – Namoi Valley. Department of Infrastructure, Planning and Natural Resources. Report prepared for the Namoi Catchment Management Authority.

Mawhinney, W. (2005). Water quality in the Namoi Catchment – 2003/2004. New South Wales Department of Natural Resources. ISBN 0 7347 5619 4.

Murray-Darling Basin Commission. (2001). Basin salinity management strategy 2001 – 2015. Murray-Darling Basin Ministerial Council, Canberra. ISBN 1 876830 17 4.

Muschal, M. (2001). Central and North West Regions water quality program. 1999-2000 report on pesticides monitoring. New South Wales Department of Land and Water Conservation, Parramatta. ISSN 1327-1032.



Muschal, M. and Warne, M. St. J. (2003). Risk posed by pesticides to aquatic organisms in rivers of northern inland New South Wales, Australia. Human and Ecological Risk Assessment, 9: 1765-1787.

Namoi Catchment Management Authority. (2007). Namoi catchment action plan part B - natural resource management plan. Namoi Catchment Management Authority, Gunnedah.

Preece, R. (1998). Key sites water quality program. NSW river water quality trends July 1992 to June 1997. Department of Land and Water Conservation. CNR 98.028.

Rattray, D.J., Freebairn. D.M. and Gurner. N.C. (2006). Best management practices for residual herbicides and water quality. Department of Natural Resources, Mines and Water. ISBN 1 74172 244 6.

Raupach, M.R., Briggs, P.R., Ford, P.W., Leys, J.F., Muschal, M., Cooper, B., and Edge, V.E. (2001). Endosulfan transport: I. Integrative assessment of airborne and waterborne pathways. Journal of Environmental Quality, 30: 714-728.

Rissik, D., van Sendon, D., Doherty, M., Ingleton, T., Ajani, P., Bowling, L., Gibbs, M., Gladstone, M., Kobayoshi, T., Suthers, I., and Froneman, W. (2009) Plankton related environmental and water quality issues pp 39-72. In: Suthers, I.M. and Rissick, D. (eds) Plankton: a guide to their ecology and monitoring for water quality. CSIRO, Melbourne.

STATISTICA®. (2008) StatSoft.

Timms, W. (1997). Liverpool Plains water quality project. 1996/97 Report on Groundwater Quality. Department of Land and Water Conservation. CNR97.108.



Appendix 1 - Pesticides screened for Namoi Water Quality Project

Chemical Name Usage

2,4,5-T Herbicide

2,4-D Herbicide

2,4-DB Herbicide

Alpha Cypermethrin Insecticide

Amitraz Insecticide

Atrazine Herbicide

Chloropyrifos Insecticide

Deltamethrin Insecticide

Demeton - S - Methyl Insecticide

Desethylatrazine Herbicide breakdown product

Diazinon Insecticide

Dicamba Herbicide

Dicofol Insecticide

Dimethoate Insecticide

Disulfoton Insecticide

Diuron Herbicide

Endosulfan - alpha Insecticide

Endosulfan - beta Insecticide

Endosulfan - sulfate Insecticide breakdown product

Esfenalerate Insecticide

Fipronil Insecticide

Fluazifop Herbicide

Fluometuron Herbicide

Fluvalinate Insecticide

Haloxyfop Herbicide

Hydroxyatrazine Herbicide breakdown product

Malathion Insecticide

MCPA Herbicide

Metolachlor Herbicide

Molinate Herbicide

Omethoate Insecticide

Parathion Insecticide

Parathion-methyl Insecticide

Pendimethalin Herbicide

Permethrin Insecticide

Profenofos Insecticide

Prometryn Herbicide




Chemical Name Usage

Propargite Insecticide

Simazine Herbicide

Sulprofos Insecticide

Thidiazuron Defoliant

Thiodicarb Insecticide

Trifluralin Herbicide


Appendix 2 - NSW Office of Water, laboratory water analysis methods

Laboratory water analysis methods for basic indicators

Indicator Lab Method Reference

Preparation and Source Method Detection limit

Electrical conductivity 54078 APHA 2510 B 1 µS/cm

Turbidity 54061 APHA 2130 B 0.1 NTU

Total nitrogen 54105 Alkaline persulphate digestion

APHA 4500-NO3-F

0.05 mg/L

Total phosphorus 54105 Alkaline persulphate digestion

APHA-4500 P-F

0.005 mg/L

Laboratory water analysis methods for major ions

Indicator Lab Method Reference

Preparation and Source Method Detection limit

Sodium - soluble 54085 APHA 3120B 0.05 mg/L

Calcium - soluble 54085 APHA 3120B 0.05 mg/L

Potassium soluble 54085 APHA 3120B 0.05 mg/L

Magnesium - soluble 54085 APHA 3120B 0.02 mg/L

Alkalinity as Bicarbonate (HCO3

-), 54082 APHA 2320B 1.0 mg/L

Sulphate 54080 APHA 4110B 0.5 mg/L

Chloride 54080 APHA 4110B 0.2 mg/L

Laboratory water analysis methods for pesticides

Analysis Lab Method Reference Source Method

Dichloromethane extraction of water samples 54042 USEPA 3510 C

Solid phase extraction of water samples 54042 / 54045 -

Analysis of Organic Acid Herbicides by Gas Chromatography - Mass Spectrometry

54053 -

Determination of pesticides using gas chromatography - mass selective detector

54051 / 54223 USEPA 625 / 8270C

Determination of phenylurea herbicides by high performance liquid chromatography

54054 -

References

American Public Health Association, (2005), “Standard methods for the examination of water and wastewater”, 21st Edition, American Public Health Association, USA.

Method 3510C – Separatory funnel liquid/liquid extraction, Ch 4.2.1, SW846 – Test methods for evaluating solid wastes- Physical and chemical methods. USEPA – 1996.

Base/Neutrals and Acids – Method 625. Test methods for organic chemical analysis of municipal and industrial wastewater. EPA 600/4-82-057, 1982.

Method 8270C – Semivolatile Organic Compounds by Gas Chromatography/Mass Spectrometry. Test Methods for evaluating Solid Waste. EPA 530/SW846 3rd Edition November 1986.



Appendix 3 - Summary statistics for basic water quality data by site

Electrical conductivity (µS/cm)

Station No n Min 25th

percentile Median

75th percentile

Max

419004 33 276 334 386 449 693

419045 37 310 348 356 375 406

419024 60 210 405 443 507 609

419073 58 287 570 708 811 1090

419006 60 318 710 929 1080 1370

419016 56 197 303 371 433 849

419097 17 516 835 880 1130 1170

419031 47 300 458 624 774 1240

419043 48 326 356 378 441 817

419071 60 87 120 129 148 264

419011 60 113 191 289 443 802

419022 60 116 220 396 471 745

419007 56 249 287 387 460 587

419027 53 201 658 1110 1470 4050

419084 31 304 501 928 1460 4940

419033 48 348 1058 1330 1625 2020

419032 39 168 272 363 448 711

419001 60 177 441 482 617 862

419051 44 249 320 378 406 514

419905 5 148 184 185 192 327

419003 60 184 382 466 507 733

419039 60 200 374 462 541 820

419059 57 159 344 458 546 761

419064 32 236 373 466 546 732

419049 39 268 468 561 619 1060

41910222 10 76 119 140 153 173

419021 53 90 326 465 530 784

419026 50 96 325 413 521 1060

419057 55 193 341 389 527 936



Turbidity (NTU)


percentile Median

75th percentile

Max

419004 34 1 3 5 8 60

419045 38 2 3 4 8 33

419024 60 5 8 10 15 85

419073 58 3 16 27 35 230

419006 60 12 26 37 45 450

419016 56 1 2 4 7 29

419097 17 1 3 6 15 1200

419031 58 1 3 7 17 70

419043 59 1 3 4 6 21

419071 60 1 3 4 8 120

419011 60 2 5 7 14 330

419022 60 2 7 12 18 400

419007 56 2 5 7 9 100

419027 53 9 22 33 55 190

419084 31 10 38 65 110 418

419033 48 6 16 24 35 172

419032 39 38 86 150 225 636

419001 60 7 14 21 31 160

419051 44 2 4 6 18 380

419905 5 17 57 76 82 130

419003 60 9 17 30 39 1300

419039 60 10 25 33 58 889

419059 57 6 20 29 40 600

419064 32 12 34 73 89 345

419049 39 20 70 110 155 433

41910222 10 90 134 144 165 254

419021 53 12 36 50 85 500

419026 50 17 54 82 151 700

419057 55 17 40 60 110 610



Total phosphorus (mg/L)


percentile Median

75th percentile

Max

419004 34 0.010 0.033 0.046 0.066 0.111

419045 38 0.023 0.031 0.049 0.056 0.209

419024 60 0.014 0.026 0.033 0.043 0.149

419073 58 0.049 0.131 0.195 0.778 1.840

419006 60 0.052 0.094 0.137 0.180 0.557

419016 56 0.006 0.014 0.029 0.044 0.122

419097 17 0.066 0.079 0.089 0.107 0.295

419031 59 0.008 0.025 0.041 0.053 0.250

419043 58 0.015 0.020 0.026 0.040 0.099

419071 60 0.013 0.029 0.043 0.076 0.730

419011 60 0.007 0.023 0.037 0.058 0.213

419022 60 0.015 0.024 0.038 0.058 0.195

419007 56 0.014 0.033 0.041 0.050 0.113

419027 53 0.041 0.120 0.181 0.302 1.540

419084 31 0.100 0.209 0.373 0.484 0.742

419033 48 0.039 0.077 0.098 0.144 1.140

419032 39 0.106 0.213 0.261 0.318 0.572

419001 60 0.032 0.050 0.067 0.092 0.265

419051 44 0.038 0.110 0.127 0.149 0.726

419905 5 0.061 0.063 0.073 0.099 0.107

419003 60 0.053 0.079 0.104 0.151 0.570

419039 60 0.054 0.094 0.123 0.184 0.659

419059 56 0.040 0.079 0.093 0.139 0.663

419064 32 0.060 0.126 0.157 0.176 0.375

419049 39 0.015 0.209 0.286 0.384 2.050

41910222 9 0.094 0.116 0.139 0.163 0.223

419021 53 0.042 0.065 0.087 0.111 0.332

419026 50 0.053 0.082 0.106 0.129 0.364

419057 55 0.013 0.086 0.105 0.150 0.363




Total nitrogen (mg/L)


percentile Median

75th percentile

Max

419004 34 0.06 0.16 0.23 0.33 1.50

419045 38 0.31 0.43 0.53 0.70 1.80

419024 60 0.09 0.21 0.29 0.40 1.60

419073 58 0.49 0.96 1.55 2.28 6.40

419006 60 0.29 0.56 0.72 1.03 3.30

419016 56 0.15 0.29 0.41 0.61 1.60

419097 16 0.14 0.27 0.31 0.34 1.60

419031 58 0.08 0.19 0.28 0.46 1.40

419043 59 0.36 0.51 0.60 0.75 1.10

419071 60 0.21 0.39 0.54 0.65 1.80

419011 60 0.23 0.38 0.53 0.70 1.40

419022 60 0.21 0.37 0.45 0.59 1.40

419007 56 0.33 0.62 0.75 0.94 14.00

419027 53 0.29 0.83 1.30 1.60 12.00

419084 31 0.46 1.30 1.90 3.30 6.70

419033 48 0.09 0.32 0.43 0.73 4.40

419032 39 0.37 1.30 1.50 1.85 2.80

419001 60 0.29 0.47 0.56 0.65 1.60

419051 44 0.13 0.24 0.31 0.45 1.70

419905 5 0.52 0.57 0.62 0.78 0.91

419003 60 0.23 0.45 0.50 0.59 2.20

419039 59 0.26 0.48 0.55 0.75 2.50

419059 56 0.21 0.47 0.53 0.65 2.30

419064 32 0.47 0.64 0.71 0.86 1.80

419049 39 0.66 1.15 1.40 2.15 18.00

41910222 9 0.65 0.99 1.20 1.30 1.80

419021 53 0.24 0.44 0.52 0.68 1.90

419026 50 0.35 0.52 0.61 0.76 2.00

419057 55 0.13 0.61 0.74 0.94 3.70

n = Number of observations

Min/Max = Minimum and maximum results for study period

Median = Results exceeded by 50% of results during the study period

25th/75th Percentile = represents the middle 50% of the data collected during the study period

namoi water quality project 2002-2007 - final report€¦ · westerly direction from the highest...

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