Menindee fish deaths follow up: Darling-Barka River water tests

The NSW Environment Protection Authority (EPA) is testing water samples from the Darling-Barka River in response to the major fish deaths at Menindee in mid-March 2023. This testing forms part of the EPA’s investigation into the cause of the fish deaths.

Test results for water and fish samples, with links to laboratory reports are listed below.

Printed copies of test results are distributed through outlets in Menindee (Police Station, Post Office, Medical Centre, cafes and the local supermarket).

Summary reports

The NSW Environment Protection Authority (EPA) collected three water samples on 24 April 2023 at Menindee along the Darling-Barka River.

Samples were checked for pesticides, excess nitrogen and phosphorus, ammonia, metals, bacteria, algae and algal toxins.

Summary

Pesticides

Samples were scanned for more than 600 pesticides. None were detected.

Nitrogen and phosphorus

Nitrogen and phosphorous levels are high. If nitrogen and phosphorus stay high they can cause algal blooms.

Algae and algal toxins

Algae, including blue-green algae, and the algal toxin Cylindrospermopsin was detected in all three samples collected from the Darling-Barka River at Menindee.

An ‘amber alert’ is in place in the Darling-Barka River at Menindee as of 10 May 2023.

Information about algae alerts is available at https://www.waternsw.com.au/water-services/water-quality/algae-alerts

Metals

All metals in the Darling-Barka River samples were under the levels set to protect water life.

Bacterial

The concentrations of the bacterial indicator, enterococci, are below guideline values for recreational use (NHMRC 2008).

Sample locations

Water was sampled on 24 April 2023 from three locations on the Darling-Barka River at Menindee.

  • Sample 1 – approximately 840m NE of Menindee Golf Club
  • Sample 2 – end of Maiden St
  • Sample 3 – beneath Menindee St bridge
Map of Menindee showing sampling sites 

More sampling

The EPA is conducting regular water quality monitoring on the Darling-Barka River from upstream of Menindee to Pooncarie as well as the Great Darling Anabranch. The test results from these samples will also be published on this website.

In-field measurements

At the time of sampling, the EPA collected in-field measurements for pH, dissolved oxygen, conductivity, temperature and turbidity.

All parameters are within the expected ranges.

Sample name Location Temp (°C) Dissolved oxygen (mg/L) Electrical conductivity (µS/cm) pH Turbidity (NTU)

1

approximately 840m NE of Menindee Golf Club

19.0

8.0

504

8.2

158

2

End of Maiden St

19.0

6.6

506

8.1

154

3

Beneath Menindee St bridge

19.0

5.9

510

8.0

167

Nitrogen, phosphorus and ammonia

Sample results show that total nitrogen and total phosphorous are higher than the acceptable levels given for lowland river ecosystems in NSW (ANZG 2018, which are in agreement with the regionally specific set of guideline values for the Murray-Darling outlined in the Basin Plan 2012). Total nitrogen was detected at three times higher than the guideline value while total phosphorous was detected at four times higher.  Algal blooms are possible if these nutrients remain elevated.

Bacteria convert nitrogen compounds such as ammonia into nitrite and nitrate. These compounds can harm aquatic organisms. Ammonia was well below the Australian and New Zealand water quality guidelines for toxicity. While the levels would not be expected to be harmful to fish, the ammonia could promote growth in algae and macrophytes. The ammonia is likely to be from river sources including rotting fish and flood organic matter rather than diffuse inputs from surrounding land.

Algae and algal toxins

A wide variety of algae was tested for. There were positive detections in all samples for a range of algal species, including blue-green algae. The algal toxin Cylindrospermopsin was detected in all samples.

The algae levels detected fall within the ‘amber’ alert levels. An ‘amber alert’ is in place in the Darling Barka River at Menindee as of 10 May 2023.

Pesticides

As noted above, a pesticide screening test that scanned for over 600 pesticides was completed for samples from all three locations. All samples came back negative for pesticide detection.

Metals

Many metals are vital for humans and animals to stay healthy and only pose a risk if they are found at high levels in the environment. Concentrations of key metals found in water are below.

Total metals have been compared to recreational water quality guidelines and dissolved metals have been compared to ecological water quality guidelines as per the National Health and Medical Research Council (NHMRC) recreational and Australian and New Zealand Water Quality (ANZG) guidelines, respectively.

Total metals provide a more conservative estimate of exposure from recreational use whereas dissolved metals are used for ecological assessments as this is the bioavailable fraction of the metal (the part that is toxic to organisms).

Metal in Water NHMRC (2008)2 Sample (total acid-extractable metals)
Recreational Water Guidelines Sample 1 Sample 2 Sample 3
(mg/L) (mg/L) (mg/L) (mg/L)

Aluminium

No value

2.7

2.6

3.8

Arsenic

0.07

0.003

0.003

0.003

Chromium

0.5

0.003

0.003

0.004

Cobalt

No value

0.0016

0.0017

0.0020

Copper

20

0.0029

0.0029

0.0033

Lead

0.1

0.0010

0.0013

0.0014

Nickel

0.2

0.0048

0.0049

0.0055

Zinc

30

0.005

0.005

0.006

2NHMRC (2008) Guidelines for managing risks in recreational waters (10 x drinking water guideline value, Table 9.3)

 

Metal in Water ANZG 20183 Sample (dissolved metals)
Water Quality Guideline for aquatic ecosystems (95% species protection) Sample 1 Sample 2 Sample 3
(mg/L) (mg/L) (mg/L) (mg/L)

Aluminium

0.055

<0.04

<0.04

<0.04

Arsenic

0.013

0.002

0.002

0.002

Cadmium

0.0002

<0.0001

<0.0001

<0.0001

Chromium

0.001

<0.001

<0.001

<0.001

Cobalt

No value

0.0003

0.0002

0.0002

Copper

0.0014

0.0014

0.0013

0.0010

Lead

0.0034

<0.0001

<0.0001

<0.0001

Manganese

1.9

<0.001

<0.001

<0.001

Nickel

0.011

0.0031

0.0031

0.0028

Selenium

0.005

<0.005

<0.005

<0.005

Silver

0.0005

<0.0001

<0.0001

<0.0001

Zinc

0.008

<0.001

<0.001

<0.001

3ANZG (2018). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia.

References

ANZG (2018), Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia. Available at www.waterquality.gov.au/anz-guidelines

Basin Plan (2012), Schedule 11, Water Act 2007, Murray-Darling Basin Authority, Commonwealth of Australia

NHMRC (2008), Guidelines for managing risks in recreational waters, Australian Government National Health and Medical Research Council

NSW Department of Primary Industries (DPI) Fisheries collected 5 samples of golden perch (Macquaria ambigua) from the Darling-Barka River at Pooncarie on 28 March.

The gastrointestinal tract and gills of the fish were analysed for metals and pesticides. The gastrointestinal tract can show what chemicals have been ingested by the fish and the gills give an indication of overall exposure from the surrounding water.

Pesticides

Samples were scanned for more than 600 pesticides. None were detected.

Metals

Many metals are vital for humans and animals to stay healthy and only pose a risk if they are found at high levels in the environment.

The only metals found in the gastrointestinal tract of the fish were zinc and mercury. These metals are known to bioaccumulate in fish. No gastrointestinal tract data are available as background in NSW, but these concentrations are below concentrations reported internationally.

Zinc and mercury were also found in the gills of the fish. This indicates some recent exposure to these metals from the water. However, water concentrations were all below water quality guidelines indicating these metals will not have adversely impacted the health of the fish.

Heavy Metal Reported mean concentration (mg/kg) in international literature for gastrointestinal tract Reported mean concentration (mg/kg) in international literature for gills Concentration in the gastrointestinal tract (mg/kg) Concentration in gills (mg/kg)

Mercury

0.02-3.6

(12 fish species with varying food regimes)1

0.007 - 0.03

(perch)2

0.044-0.055

0.023-0.036

Zinc

11-559

(pike and bream)3

12-171

(pike and bream)3

10-15

21-28


1
Regine 2006     2 Luczynska 2016     3 Rajkowska 2013

Download the full test reports: 28 March

The full report (with individual's names and addresses redacted for privacy) are available for download

Sample locations

Fish samples were collected from two locations near Pooncarie on 28 March 2023.

  • Sample 1 – Downstream of Pooncarie Weir
  • Sample 2 – Pooncarie Cafe

map showing two testing sites at Pooncarie 28 March 2023

References

FSANZ. 2001. Generally expected levels (GELs) for Metal Contaminants - Additional guidelines to maximum levels in Standard 1.4..1 - Contaminants and Natural Toxicants. Australian New Zealand Food Standards Code.

1Regine M.B., Gilles D., Yannick D. and Alain B. (2006). Mercury distribution in fish organs and food regimes: Significant relationships from twelve species collected in French Guiana (Amazonian basin). Science of the Total Environment. 368: 262-270

2Luczynska J., Luczynski M. J. and Paszczyk B. (2016). Assessment of mercury in muscles, liver and gills of marine and freshwater fish. Journal of Elementology. 21(1): 113-129

3Rajkowska M. and Protasowicki M. (2013). Distribution of metals (Fe, Mn, Zn, Cu) in fish tissues in two lakes of different trophy in Northwestern Poland. Environmental Monitoring and Assessment. 185(4): 3493-3502

WaterNSW collected six water samples for the EPA on 11 April 2023 downstream of Menindee on the Darling-Barka River,  the Murray River and the Great Darling Anabranch.

Samples were checked for pesticides, excess nitrogen and phosphorus, ammonia, metals, bacteria, algae and algal toxins.

Summary

Pesticides

Samples were scanned for more than 600 pesticides. None were detected.

Nitrogen and phosphorus

Nitrogen and phosphorous levels are high. If nitrogen and phosphorus stay high they can cause algal blooms.

Algae and algal toxins

Algae, including blue-green algae, were detected in all six samples. A ‘red alert’ is in place in the Murray River at Fort Courage and in the Great Darling Anabranch at Silver City Highway as of 28 April 2023. The algal toxin Cylindrospermopsin was detected in samples collected from the Murray River in these locations.

An ‘amber alert’ is in place in the Murray River at Merbein and in the Darling-Barka River at Merbein, Ellerslie and Burtundy.

Information about algae alerts is available at https://www.waternsw.com.au/water-services/water-quality/algae-alerts

Metals

Copper remains slightly above the level set to protect water life but well below the level harmful to fish. All other metals were under the levels set to protect water life.

Bacterial

The concentration of the bacterial indicator, enterococci, exceeded guideline values for recreational use (NHMRC 2008) at two sites in the Murray River at Fort Courage and in the Darling-Barka River at Ellerslie.

Sample locations

Water was sampled on 11 April 2023 from six locations downstream of Menindee on the Darling-Barka River, the Murray River and the Great Darling Anabranch:

  • Sample 1 – Murray River at Merbein Pump Station
  • Sample 2 – Darling-Barka River at Tapio
  • Sample 3 – Darling-Barka River at Ellerslie
  • Sample 4 – Darling-Barka River at Burtundy
  • Sample 5 – Great Darling Anabranch at Silver City Highway
  • Sample 6 – Murray River at Fort Courage

Map showing the six sampling sites downstream of Menindee on  11 April 2023

More sampling

The EPA is conducting regular water quality monitoring on the Darling-Barka River from upstream of Menindee to Pooncarie as well as the Great Darling Anabranch. The test results from these samples will also be published on this website.

In-field measurements

At the time of sampling, WaterNSW collected in-field measurements for pH, dissolved oxygen, conductivity, temperature and turbidity.

Dissolved oxygen ranged from 5.6mg/L to 10.3mg/L at the six locations. Native fish and other large aquatic organisms require at least 2mg/L of dissolved oxygen to survive but may begin to suffer if levels are below 4 to 5mg/L for prolonged periods.

pH was outside the guideline value in the Murray River at Merbein Pump Station and Fort Courage, and in the Great Darling Anabranch at Silver City Highway. 

All other parameters are within the expected ranges.

Sample name Location Temp (°C) Dissolved oxygen (mg/L) Electrical conductivity (µS/cm) pH Turbidity (NTU)

1

Murray River at Merbein Pump Station

19.0

9.1

292

8.2

14

2

Darling-Barka River at Tapio

19.1

6.0

449

7.9

148

3

Darling-Barka River at Ellerslie

19.2

5.7

458

7.9

183

4

Darling-Barka River at Burtundy

19.3

5.6

468

7.8

163

5

Great Darling Anabranch at Silver City Highway

18.7

10.3

489

8.9

61

6

Murray River at Fort Courage

18.7

8.8

433

8.3

69

 

Nitrogen, phosphorus and ammonia

Sample results show that total nitrogen and total phosphorous are higher than the acceptable levels given for lowland river ecosystems in NSW (ANZG 2018, which are in agreement with the regionally specific set of guideline values for the Murray-Darling outlined in the Basin Plan 2012). Total nitrogen was detected at five times higher than the guideline value while total phosphorous was detected at ten times higher. Algal blooms are possible if these nutrients remain elevated.

Bacteria convert nitrogen compounds such as ammonia into nitrite and nitrate. These compounds can harm aquatic organisms. The water samples from 11 April show high levels of nitrite and nitrate, and there is a potential for further harm to aquatic organisms.

Ammonia was well below the Australian and New Zealand water quality guidelines for toxicity and as a stressor (i.e. nutrient).  The levels would not be expected to be harmful to fish or promote growth in algae and aquatic plants.

Algae and algal toxins

A wide variety of algae was tested for. There were positive detections in all samples for a range of algal species, including blue-green algae. The algal toxin Cylindrospermopsin was detected in the samples collected from the Murray River at Fort Courage and the Great Darling Anabranch at Silver City Highway.

The algae levels detected fall within the ‘amber’ to ‘red’ alert levels. A ‘red alert’ is in place in the Murray River at Fort Courage and in the Great Darling Anabranch at Silver City Highway as of 28 April 2023. An  ‘amber alert’ is in place in the Murray River at Merbein and in the Darling Barka River at Merbein, Ellerslie and Burtundy.

Pesticides

As noted above, a pesticide screening test that scanned for over 600 pesticides was completed for samples from all six locations. All samples came back negative for pesticide detection.

Metals

Many metals are vital for humans and animals to stay healthy and only pose a risk if they are found at high levels in the environment. Concentrations of key metals found in water are below.

Total metals have been compared to recreational water quality guidelines and dissolved metals have been compared to ecological water quality guidelines as per the National Health and Medical Research Council (NHMRC) recreational and Australian and New Zealand Water Quality (ANZG) guidelines, respectively.

Total metals provide a more conservative estimate of exposure from recreational use whereas dissolved metals are used for ecological assessments as this is the bioavailable fraction of the metal (the part that is toxic to organisms).

Metal in Water NHMRC (2008)2 Sample (total acid-extractable metals)
Recreational Water Guidelines Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)

Aluminium

No value

0.29

4.7

4.9

4.3

1.7

2.2

Arsenic

0.07

0.001

0.005

0.005

0.005

0.006

0.005

Chromium

0.5

<0.001

0.005

0.005

0.004

0.002

0.002

Cobalt

No value

0.0005

0.0020

0.0024

0.0021

0.0019

0.0020

Copper

20

0.0011

0.0060

0.0055

0.0051

0.0033

0.0032

Lead

0.1

0.0004

0.0017

0.0021

0.0018

0.0010

0.0011

Nickel

0.2

0.0010

0.0068

0.0070

0.0067

0.0043

0.0042

Zinc

30

0.001

0.011

0.010

0.009

0.005

0.005

2NHMRC (2008) Guidelines for managing risks in recreational waters (10 x drinking water guideline value, Table 9.3)

 

Metal in Water

 

 

 

 

ANZG 20183 Sample (dissolved metals)
Water Quality Guideline for aquatic ecosystems (95% species protection)

Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

Sample 6

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

Aluminium

0.055

<0.04

<0.04

<0.04

<0.04

<0.04

<0.04

Arsenic

0.013

<0.001

0.005

0.004

0.004

0.006

0.004

Cadmium

0.0002

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Chromium

0.001

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

Cobalt

No value

<0.0001

0.0002

0.0002

0.0002

0.0007

0.0005

Copper

0.0014

0.0006

0.0022 0.0019 0.0018

0.0014

0.0012

Lead

0.0034

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Manganese

1.9

<0.001

0.003

<0.001

<0.001

<0.001

<0.001

Nickel

0.011

0.0007

0.0032

0.0033

0.0031

0.0024

0.0022

Selenium

0.005

<0.005

<0.005

<0.005

<0.005

<0.005

<0.005

Silver

0.0005

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Zinc

0.008

<0.001

0.002

<0.001

<0.001

<0.001

<0.001

3ANZG (2018). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia.

References

ANZG (2018), Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia. Available at www.waterquality.gov.au/anz-guidelines.

Basin Plan (2012), Schedule 11, Water Act 2007, Murray-Darling Basin Authority, Commonwealth of Australia.

NHMRC (2008), Guidelines for managing risks in recreational waters, Australian Government National Health and Medical Research Council.

The EPA collected two water samples on 4 April 2023 downstream of Menindee at Pooncarie.

Samples were checked for pesticides, excess nitrogen and phosphorus, ammonia, metals, bacteria, algae and algal toxins.

Summary

Pesticides

Samples were scanned for more than 600 pesticides. None were detected.

Nitrogen and phosphorus

Nitrogen and phosphorus remain at high levels. The water samples were taken after many fish had died so the high levels could be due to rotting fish. If nitrogen and phosphorus stay high they can cause algal blooms.

Algae and algal toxins

Algae, including blue-green algae, were detected in both samples. An ‘amber alert’ remains in place for the Darling-Barka River at Menindee and Pooncarie as of 24 April 2023. A low concentration of the algal toxin Cylindrospermopsin was detected in the sample collected from Karoola Reach.

Information about algae alerts is available at https://www.waternsw.com.au/water-services/water-quality/algae-alerts

Metals

Copper was slightly above the level set to protect water life but well below the level harmful to fish. All other metals were under the levels set to protect water life.

Bacterial

The concentrations of bacterial indicators, faecal coliforms and enterococci, are below guideline values for recreational use (NHMRC 2008).

Sample locations

Water was sampled on 4 April from two locations on the Darling-Barka River at Pooncarie:

  • Sample 1 – Karoola Reach, approximately 60 kilometres north of Pooncarie
  • Sample 2 – Pooncarie Bilbarka Park
Menindee fish kill sampling sites, Pooncarie 4 April 2023 

More sampling

WaterNSW has collected more water samples for the EPA from the Darling-Barka River on 11 April 2023. The test results for these samples will also be published on the EPA webpage.

In-field measurements

At the time of sampling, the EPA collected in-field measurements for pH, dissolved oxygen, conductivity, temperature and turbidity.

Dissolved oxygen at Site 1 was 2.53mg/L and at Site 2 was 3.11mg/L. Native fish and other large aquatic organisms require at least 2mg/L of dissolved oxygen to survive but may begin to suffer if levels are below 4 to 5mg/L for prolonged periods.

All other parameters were within the expected ranges.

Sample name

Location

Temp (°C)

Dissolved oxygen (mg/L)

Electrical conductivity (µS/cm)

pH

Turbidity (NTU)

1

Karoola Reach, approximately 60km upstream from Pooncarie

20.6

3.11

419

7.72

109.5

2

Pooncarie Bilbarka Park

21.1

2.53

404

7.59

115.9

Nitrogen and phosphorus

Sample results show that total nitrogen and total phosphorous are higher than the acceptable levels given for lowland river ecosystems in NSW (ANZG 2018, which are in agreement with the regionally specific set of guideline values for the Murray-Darling outlined in the Basin Plan 2012). Total nitrogen was detected at five times higher than the guideline value while total phosphorous was detected at seven times higher. Algal blooms are possible if these nutrients remain elevated.

Bacteria convert nitrogen compounds such as ammonia into nitrite and nitrate. These compounds can harm aquatic organisms. The water samples from 4 April show high levels of nitrite and nitrate, and there is a potential for further harm to aquatic organisms.

Ammonia was well below the Australian and New Zealand water quality guidelines for toxicity. While the levels would not be expected to be harmful to fish, the ammonia could promote growth in algae and aquatic plants. The ammonia is likely to be from river sources including rotting fish and flood detritus rather than diffuse inputs from surrounding land.

Algae and algal toxins

A wide variety of algae was tested for. There were positive detections in both samples for a range of algal species, including blue-green algae, and common toxins produced by blue-green algae. A low concentration of the algal toxin Cylindrospermopsin was detected in the sample collected from Karoola Reach.

The algae levels detected fall within the ‘green’ to ‘amber’ alert levels. An amber alert remains in place at Menindee and Pooncarie as of 24 April 2023.

Pesticides

As noted above, a pesticide screening test that scanned for over 600 pesticides was completed for samples at both locations. Both samples came back negative for pesticide detection.

Metals

Many metals are vital for humans and animals to stay healthy and only pose a risk if they are found at high levels in the environment. Concentrations of key metals found in water are below.

Total metals have been compared to recreational water quality guidelines and dissolved metals have been compared to ecological water quality guidelines as per the National Health and Medical Research Council (NHMRC) recreational and Australian and New Zealand Water Quality (ANZG) guidelines, respectively.

Total metals provide a more conservative estimate of exposure from recreational use whereas dissolved metals are used for ecological assessments as this is the bioavailable fraction of the metal (the part that is toxic to organisms).

Metal in Water

NHMRC (2008)2

Sample (total acid-extractable metals)

Recreational Water Guidelines

Sample 1

Sample 2

(mg/L)

(mg/L)

(mg/L)

Aluminium

No value

5.7

5.3

Arsenic

0.07

0.006

0.006

Chromium

0.5

0.008

0.007

Cobalt

No value

0.0031

0.0026

Copper

20

0.0063

0.0060

Lead

0.1

0.0024

0.0022

Nickel

0.2

0.0085

0.0079

Zinc

30

0.012

0.012

2NHMRC (2008) Guidelines for managing risks in recreational waters (10 x drinking water guideline value, Table 9.3)

Metal in Water

ANZG 20183

Sample (dissolved metals)

Water Quality Guideline for aquatic ecosystems (95% species protection)

Sample 1

Sample 2

(mg/L)

(mg/L)

(mg/L)

Aluminium

0.055

<0.04

<0.04

Arsenic

0.013

0.005

0.005

Cadmium

0.0002

<0.0001

<0.0001

Chromium

0.001

<0.001

<0.001

Cobalt

No value

0.0003

0.0002

Copper

0.0014

0.0018

0.0018

Lead

0.0034

<0.0001

<0.0001

Manganese

1.9

<0.001

<0.001

Nickel

0.011

0.0031

0.0030

Selenium

0.005

<0.005

<0.005

Silver

0.0005

<0.0001

<0.0001

Zinc

0.008

0.001

<0.001

3ANZG (2018). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia.

 

WaterNSW collected five water samples for the EPA on 3 April 2023.

Samples were checked for pesticides, excess nitrogen and phosphorus, ammonia, metals, algae and algal toxins.

Summary

Pesticides

Samples were scanned for more than 600 pesticides. None were detected.

Nitrogen and phosphorus

Nitrogen and phosphorous levels remain high. The water samples were taken after many fish had died so the high levels could be due to rotting fish. If nitrogen and phosphorus stay high they can cause algal blooms.

Algae and algal toxins

Algae, including blue-green algae, were detected in all five samples. An ‘amber alert’ remains in place for the Darling-Barka River at Menindee and Pooncarie as of 24 April 2023. No algal toxins were detected.

Information about algae alerts is available at https://www.waternsw.com.au/water-services/water-quality/algae-alerts

Metals

Copper remains slightly above the level set to protect water life but well below the level harmful to fish. All other metals were under the levels set to protect water life.

Sample locations

Water was sampled on 3 April 2023 from five locations on the Darling-Barka River between Main Weir and Weir 32:

  • Sample 1 – Downstream of the main weir at Menindee
  • Sample 2 – Menindee Water Treatment Plant
  • Sample 3 – Upstream of Menindee Creek
  • Sample 4 – Downstream of Menindee Creek
  • Sample 5 – Upstream of Weir 32 at Menindee
Menindee fish kill sampling sites, 3 April 2023 

More sampling

The EPA and WaterNSW have collected more water samples from the Darling-Barka River downstream in the Pooncarie area on 11 April 2023. The test results from these samples will also be published on the EPA webpage.

In-field measurements

At the time of sampling, WaterNSW collected in-field measurements for pH, dissolved oxygen, conductivity and temperature.

Dissolved oxygen ranged from 1.82mg/L to 7.04mg/L at the five locations. Native fish and other large aquatic organisms require at least 2mg/L of dissolved oxygen to survive but may begin to suffer if levels are below 4 to 5mg/L for prolonged periods. One of the five sample locations detected dissolved oxygen levels below 2 mg/L.

All other parameters are within the expected ranges.

Sample name

Location

Temp (°C)

Dissolved oxygen (mg/L)

Electrical conductivity (µS/cm)

pH

1

Downstream Main Weir

19.4

7.04

515

7.72

2

Water treatment plant

20.5

2.79

508

7.63

3

Upstream Menindee Creek

20.5

1.82

506

7.62

4

Downstream several kms of Menindee Creek

19.1

6.68

439.3

8.08

5

 

Upstream of Weir 32

19.4

6.39

437.6

8.04

Nitrogen, phosphorus and ammonia

Sample results show that total nitrogen and total phosphorous are higher than the acceptable levels given for lowland river ecosystems in NSW (ANZG 2018, which are in agreement with the regionally specific set of guideline values for the Murray-Darling outlined in the Basin Plan 2012). Total nitrogen was detected at four times higher than the guideline value while total phosphorous was detected at seven times higher.  Algal blooms are possible if these nutrients remain elevated.

Bacteria convert nitrogen compounds such as ammonia into nitrite and nitrate. These compounds can harm aquatic organisms. The water samples from 3 April show high levels of nitrite and nitrate, and there is a potential for further harm to aquatic organisms.

Ammonia was well below the Australian and New Zealand water quality guidelines for toxicity. While the levels would not be expected to be harmful to fish, the ammonia could promote growth in algae and aquatic plants. The ammonia is likely to be from river sources including rotting fish and flood organic matter rather than diffuse inputs from surrounding land.

Algae and algal toxins

A wide variety of algae was tested for. There were positive detections in all samples for a range of algal species, including blue-green algae.

The algae levels detected fall within the ‘green’ to ‘amber’ alert levels. An amber alert remains in place at Menindee and Pooncarie as of 24 April 2023. No algal toxins were detected.

Pesticides

As noted above, a pesticide screening test that scanned for over 600 pesticides was completed for samples from all five locations. All samples came back negative for pesticide detection.

Metals

Many metals are vital for humans and animals to stay healthy and only pose a risk if they are found at high levels in the environment. Concentrations of key metals found in water are below.

Total metals have been compared to recreational water quality guidelines and dissolved metals have been compared to ecological water quality guidelines as per the National Health and Medical Research Council (NHMRC) recreational and Australian and New Zealand Water Quality (ANZG) guidelines, respectively.

Total metals provide a more conservative estimate of exposure from recreational use whereas dissolved metals are used for ecological assessments as this is the bioavailable fraction of the metal (the part that is toxic to organisms).

Metal in Water

NHMRC (2008)2

Sample (total acid-extractable metals)

Recreational Water Guidelines

(mg/L)

Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

Aluminium

No value

2.2

3.5

3.3

4.7

4.7

Arsenic

0.07

0.003

0.003

0.003

0.005

0.005

Chromium

0.5

0.002

0.004

0.004

0.005

0.005

Cobalt

No value

0.0016

0.0021

0.0020

0.0019

0.0019

Copper

20

0.0028

0.0037

0.0035

0.0051

0.0052

Lead

0.1

0.0010

0.0017

0.0015

0.0016

0.0016

Nickel

0.2

0.0051

0.0063

0.0060

0.0063

0.0062

Zinc

30

0.005

0.007

0.007

0.009

0.009

2NHMRC (2008) Guidelines for managing risks in recreational waters (10 x drinking water guideline value, Table 9.3)

 

Metal in Water

ANZG 20183

Sample (dissolved metals)

Water Quality Guideline for aquatic ecosystems (95% species protection)

(mg/L)

Sample 1

(mg/L)

Sample 2

(mg/L)

Sample 3

(mg/L)

Sample 4

(mg/L)

Sample 5

(mg/L)

Aluminium

0.055

<0.04

<0.04

<0.04

<0.04

<0.04

Arsenic

0.013

0.003

0.003

0.003

0.003

0.003

Cadmium

0.0002

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Chromium

0.001

<0.001

<0.001

<0.001

<0.001

<0.001

Cobalt

No value

0.0002

0.0002

0.0002

0.0002

0.0002

Copper

0.0014

0.0012

0.0011

0.0010

0.0019

0.0020

Lead

0.0034

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Manganese

1.9

<0.001

<0.001

<0.001

<0.001

<0.001

Nickel

0.011

0.0032

0.0034

0.0034

0.0026

0.0026

Selenium

0.005

<0.005

<0.005

<0.005

<0.005

<0.005

Silver

0.0005

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Zinc

0.008

<0.001

<0.001

<0.001

<0.001

<0.001

3ANZG (2018). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia.

The EPA collected two water samples on 30 March downstream of Menindee at Pooncarie and approximately 60 kilometres upstream of Pooncarie.

Samples were checked for pesticides, excess nitrogen and phosphorus, metals, algae and algal toxins.

Summary

Pesticides

Samples were scanned for more than 600 pesticides. None were detected.

Nitrogen and phosphorus

Nitrogen and phosphorus remain at high levels. The water samples were taken after many fish had died so the high levels could be due to rotting fish. If nitrogen and phosphorus stay high they can cause algal blooms.

Algae

Algae, including blue-green algae, were detected in both samples. An ‘amber alert’ remains in place for the Darling River at Menindee and Pooncarie as of 20 April 2023.

Information about algae alerts is available here https://www.waternsw.com.au/water-services/water-quality/algae-alerts

Metals

Copper remains slightly above the level set to protect water life but well below the level lethal to fish. All other metals were under the levels set to protect water life.

Sample locations

Water was sampled on 30 March from two locations on the Darling River downriver of Menindee:

  • Sample 1 – Approximately 60 kilometres upstream of Pooncarie. This site is identified as DRKR on the full sample results.
  • Sample 2 – Old Wharf Pooncarie. This site is identified at DRPW on the full sample results.

Menindee fish kill water sampling sites, Pooncarie 30 March 2023

More sampling

The EPA and WaterNSW have collected more water samples from the Darling River in the Menindee area and downstream in the Pooncarie area on 3, 4 and 11 April. The test results from these samples will also be published on the EPA webpage.

In-field measurements

At the time of sampling, the EPA collected in-field measurements for pH, dissolved oxygen, conductivity, temperature and turbidity.

Dissolved oxygen ranged from 2.75 mg/L to 3.56mg/L at the two locations. Native fish and other large aquatic organisms require at least 2mg/L of dissolved oxygen to survive but may begin to suffer if levels are below 4 to 5mg/L for prolonged periods.

All other parameters are within the expected ranges.

Sample name

Location

Temp (°C)

Dissolved oxygen (mg/L)

Conductivity

(µS/cm)

pH

Turbidity (NTU)

1

Approximately 60km upstream of Pooncarie (Karoola Reach)

21.9

3.56

417

7.73

148

2

Old Wharf Pooncarie

22.2

2.75

420

7.65

114

Nitrogen, phosphorus and ammonia

Sample results show that total nitrogen and total phosphorous are higher than the acceptable levels given for lowland river ecosystems in NSW (ANZG 2018, which are in agreement with the regionally specific set of guideline values for the Murray-Darling outlined in the Basin Plan 2012). Total nitrogen was detected at six times higher than the guideline value while total phosphorous was detected at nine times higher. Algal blooms are possible if these nutrients remain elevated.

Bacteria convert nitrogen compounds such as ammonia into nitrite and nitrate. These compounds can harm aquatic organisms. The water samples from 30 March show high levels of nitrite and nitrate, and there is a potential for further harm to aquatic organisms.

Ammonia was well below the Australian and New Zealand water quality guidelines for toxicity. While the levels would not be expected to be harmful to fish, the ammonia could promote growth in algae and macrophytes. The ammonia is likely to be from river sources including rotting fish and flood detritus rather than diffuse inputs from surrounding land.

Algae and algal toxins

A wide variety of algae was tested for. There were positive detections in all samples for a range of algal species, including blue-green algae, and common toxins produced by blue-green algae.

The algae levels detected fall within the ‘green’ to ‘amber’ alert levels. An amber alert remains in place at Menindee and Pooncarie as of 20 April 2023.

Pesticides

As noted above, a pesticide screening test that scanned for over 600 pesticides was completed for samples from both locations. All samples came back negative for pesticide detection.

Metals

Many metals are vital for humans and animals to stay healthy and only pose a risk if they are found at high levels in the environment. Concentrations of key metals found in water are below.

Total metals have been compared to recreational water quality guidelines and dissolved metals have been compared to ecological water quality guidelines as per the National Health and Medical Research Council (NHMRC) recreational and Australian and New Zealand Water Quality (ANZG) guidelines, respectively.

Total metals provide a more conservative estimate of exposure from recreational use whereas dissolved metals are used for ecological assessments as this is the bioavailable fraction of the metal (the part that is toxic to organisms).

Metal in Water

NHMRC (2008)2

Sample (total acid-extractable metals)

Recreational Water Guidelines

(mg/L)

Sample 1
(mg/L)

Sample 2
(mg/L)

Aluminium

No value

3.4

3.3

Arsenic

0.07

0.005

0.006

Chromium

0.5

0.004

0.004

Cobalt

No value

0.0018

0.0019

Copper

20

0.0048

0.0049

Lead

0.1

0.0016

0.0015

Nickel

0.2

0.0061

0.0065

Zinc

30

0.008

0.008

2NHMRC (2008) Guidelines for managing risks in recreational waters (10x drinking water guideline value, Table 9.3)

 

Metal in Water

ANZG 20183

Sample (dissolved metals)

Water Quality Guideline for aquatic ecosystems (95% species protection)

(mg/L)

Sample 1

(mg/L)

Sample 2

(mg/L)

Aluminium

0.055

<0.04

<0.04

Arsenic

0.013

0.005

0.006

Cadmium

0.0002

<0.0001

<0.0001

Chromium

0.001

<0.001

<0.001

Cobalt

No value

0.0002

0.0002

Copper

0.0014

0.0019

0.0018

Lead

0.0034

<0.0001

<0.0001

Manganese

1.9

<0.001

<0.001

Nickel

0.011

0.0029

0.0031

Selenium

0.011

<0.005

<0.005

Silver

0.0005

<0.0001

<0.0001

Zinc

0.008

<0.001

<0.001

3ANZG (2018). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia. 

WaterNSW collected five water samples for the NSW Environment Protection Authority (EPA) on 30 March.

Samples were checked for pesticides, excess nitrogen and phosphorus, metals, algae and algal toxins.

Summary

Pesticides

Samples were scanned for more than 600 pesticides. None were detected.

Nitrogen and phosphorus

Nitrogen and phosphorus remain at high levels. The water samples were taken after many fish had died so the high levels could be due to rotting fish. If nitrogen and phosphorus stay high they can cause algal blooms.

Algae

Algae, including blue-green algae, were detected in five samples. An ‘amber alert’ remains in place for the Darling River at Menindee and Pooncarie as of 20 April 2023.

Information about algae alerts is available here https://www.waternsw.com.au/water-services/water-quality/algae-alerts

Metals

Copper remains slightly above the level set to protect water life but well below the level lethal to fish. All other metals were under the levels set to protect water life.

Sample locations

Water was sampled on 30 March from five locations on the Darling River between Main Weir and Weir 32:

  • Sample 2– Downstream of the main weir at Menindee.
  • Sample 3 – Menindee Water Treatment Plant
  • Sample 4 – Upstream of Menindee Creek
  • Sample 6 – Several kilometres downstream of Menindee Creek
  • Sample 7 – Downstream of Weir 32 

Menindee fish kill sampling sites 30 March 2023

Menindee fish kill sampling sites 30 March 2023

In-field measurements

At the time of sampling, WaterNSW collected in-field measurements for pH, dissolved oxygen, conductivity, temperature and turbidity.

Dissolved oxygen ranged from 0.73mg/L to 5.85mg/L at the five locations. Native fish and other large aquatic organisms require at least 2mg/L of dissolved oxygen to survive but may begin to suffer if levels are below 4 to 5mg/L for prolonged periods. Two of the five sample locations detected dissolved oxygen levels below 2 mg/L.

All other parameters are within the expected ranges.

Sample name

Location

Temp (°C)

Dissolved oxygen (mg/L)

Electrical conductivity (µS/cm)

pH

Turbidity (NTU)

2

Downstream Main Weir

21.5

5.85

515

7.69

50

3

Water treatment plant

22.3

1.4

519

7.44

55

4

Upstream Menindee Creek

22.2

0.73

499

7.46

68.1

6

Downstream several kms of Menindee Creek

21.5

5.01

443.6

7.78

97

7

 

Downstream of Weir 32

21.7

4.78

443.1

7.69

101.4

 

Nitrogen, phosphorus and ammonia

Sample results show that total nitrogen and total phosphorous are higher than the acceptable levels given for lowland river ecosystems in NSW (ANZG 2018, which are in agreement with the regionally specific set of guideline values for the Murray-Darling outlined in the Basin Plan 2012). Total nitrogen was detected at five times higher than the guideline value while total phosphorous was detected at seven times higher. Algal blooms are possible if these nutrients remain elevated.

Bacteria convert nitrogen compounds such as ammonia into nitrite and nitrate. These compounds can harm aquatic organisms. The water samples from 30 March show high levels of nitrite and nitrate, and there is a potential for further harm to aquatic organisms.

Ammonia was well below the Australian and New Zealand water quality guidelines for toxicity. While the levels would not be expected to be harmful to fish, the ammonia could promote growth in algae and aquatic plants. The ammonia is likely to be from river sources including rotting fish and flood detritus rather than diffuse inputs from surrounding land.

Algae and algal toxins

A wide variety of algae was tested for. There were positive detections in all samples for a range of algal species, including blue-green algae, and common toxins produced by blue-green algae.

The algae levels detected fall within the ‘green’ to ‘amber’ alert levels. An amber alert remains in place at Menindee and Pooncarie as of 20 April 2023.

Pesticides

As noted above, a pesticide screening test that scanned for over 600 pesticides was completed for samples from all five locations. All samples came back negative for pesticide detection.

Metals

Many metals are vital for humans and animals to stay healthy and only pose a risk if they are found at high levels in the environment. Concentrations of key metals found in water are below.

Total metals have been compared to recreational water quality guidelines and dissolved metals have been compared to ecological water quality guidelines as per the National Health and Medical Research Council (NHMRC) recreational and Australian and New Zealand Water Quality (ANZG) guidelines, respectively.

Total metals provide a more conservative estimate of exposure from recreational use whereas dissolved metals are used for ecological assessments as this is the bioavailable fraction of the metal (the part that is toxic to organisms).

Metal in Water

NHMRC (2008)2

Sample (total acid-extractable metals)

Recreational Water Guidelines

(mg/L)

Sample 2

Sample 3

Sample 4

Sample 6

Sample 7

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

Aluminium

No value

2

2.2

2.7

3.9

4.1

Arsenic

0.07

0.003

0.003

0.004

0.005

0.005

Chromium

0.5

0.003

0.003

0.003

0.005

0.005

Cobalt

No value

0.0019

0.0020

0.0018

0.0019

0.0019

Copper

20

0.0031

0.0030

0.0033

0.0049

0.0050

Lead

0.1

0.0012

0.0014

0.0015

0.0016

0.0018

Nickel

0.2

0.0054

0.0055

0.0059

0.0062

0.0065

Zinc

30

0.005

0.005

0.007

0.008

0.009

2NHMRC (2008) Guidelines for managing risks in recreational waters (10 x drinking water guideline value, Table 9.3)

Metal in Water

ANZG 20183

Sample (dissolved metals)

Water Quality Guideline for aquatic ecosystems (95% species protection)

(mg/L)

Sample 2

(mg/L)

Sample 3

(mg/L)

Sample 4

(mg/L)

Sample 6

(mg/L)

Sample 7

(mg/L)

Aluminium

0.055

<0.04

<0.04

<0.04

<0.04

<0.04

Arsenic

0.013

0.003

0.003

0.003

0.005

0.005

Cadmium

0.0002

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Chromium

0.001

<0.001

<0.001

<0.001

<0.001

<0.001

Cobalt

No value

0.0002

0.0003

0.0002

0.0002

0.0002

Copper

0.0014

0.0011

0.0007

0.0009

0.0018

0.0018

Lead

0.0034

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Manganese

1.9

<0.001

<0.001

<0.001

<0.001

<0.001

Nickel

0.011

0.0031

0.0032

0.0035

0.0028

0.0029

Selenium

0.011

<0.005

<0.005

<0.005

<0.005

<0.005

Silver

0.0005

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Zinc

0.008

<0.001

<0.001

<0.001

<0.001

<0.001

3ANZG (2018). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia. 

Summary

Pesticides

Samples were scanned for more than 600 pesticides. None were detected.

Nitrogen and phosphorus

Nitrogen and phosphorus were at high levels. The water samples were taken after many fish had died so the high levels could be due to rotting fish. If nitrogen and phosphorus stay high they can cause algal blooms.

Algae

Algae, including blue-green algae, were detected in all six samples. An ‘amber alert’ is now in place for this part of the river. This means:

  • people should not drink untreated river water.
Avoid contact with river water if you see scum on top.

Metals

Levels of metals were within the limits set for recreational use – that is, swimming and canoeing are OK. Copper was above the level set to protect water life but well below the level harmful to fish. All other metals were under the levels set to protect water life.

Sample locations

Water was sampled on 21 March from six locations on the Darling River between the outlet at Main Weir and Weir 32:

  • Sample 1 – Outlet to Lake Pamamaroo
  • Sample 2 – Downstream Main Weir
  • Sample 3 – Darling River at the Menindee Rail Bridge
  • Sample 4 – Darling River upstream of Menindee Creek
  • Sample 5 – Darling River several kilometres downstream from Menindee outlet. 
  • Sample 6 – Weir 32

map of Meninde area showing points on the Murray river where samples were collected between the outlet at Main Weir and Weir 32

In-field measurements

At the time of sampling, WaterNSW collected in-field measurements for pH, dissolved oxygen, conductivity, temperature and turbidity.

Dissolved oxygen ranged from 0.41mg/L to 5.97mg/L at the six locations. Native fish and other large aquatic organisms require at least 2mg/L of dissolved oxygen to survive but may begin to suffer if levels are below 4 to 5mg/L for prolonged periods. Three of the six sample locations detected dissolved oxygen levels below 3 mg/L.

One sample taken from the Darling River, upstream of Menindee Creek detected dissolved oxygen levels below 1mg/L. Dissolved oxygen lower than 1 mg/L can be lethal for animals that can’t move to oxygen-rich areas.

All other parameters are within the expected range.

Sample name

Location

Temp (°C)

Dissolved oxygen (mg/L)

Conductivity compensated (SPC – µS/cm)

pH

Turbidity (NTU)

1

Outlet to Lake Pamamaroo

22.6

5.97

478

7.8

109

2

DS Main Weir

23.0

1.83

529

7.5

73.3

3

Darling River at the Menindee rail bridge/town water offtake

24.5

1.21

671

7.6

61.0

4

Darling River u/s of Menindee Creek

24.4

0.41

478

7.5

45.4

5

Darling River several km downstream of Menindee outlet

22.6

4.84

420

7.9

120

6

Weir 32

22.9

4.18

421

7.8

123

Nitrogen and phosphorus

Sample results show that Total Nitrogen and Total Phosphorous are higher than the trigger values given for lowland river ecosystems in NSW (ANZG 2018). Total nitrogen was detected at eight times higher than the guideline value while total phosphorous was detected at eleven times higher. Algal blooms are possible if these nutrients remain elevated.

Bacteria convert nitrogen compounds such as ammonia into nitrite and nitrate. These compounds can harm aquatic organisms. The water samples from 21 March show high levels of ammonia, nitrite and nitrate, and there is a potential for harm to aquatic organisms.

Algae and algal toxins

A wide variety of algae was tested for. There were positive detections in all six samples for a range of algae species, including blue-green algae.

WaterNSW has advised that the algae levels detected fall within the ‘green’ to ‘amber’ alert levels. An amber alert is currently in place.

Pesticides

As noted above, a pesticide screening test that scanned for over 600 pesticides was completed for samples from all six locations. All samples came back negative for pesticide detection.

Metals

Many metals are vital for humans and animals to stay healthy and only pose a risk if they are found at high levels in the environment. Concentrations of key metals found in water are below.

Total metals have been compared to recreational water quality guidelines and dissolved metals have been compared to ecological water quality guidelines as per NHMRC and ANZECC guidelines, respectively.

Total metals provide a more conservative estimate of exposure from recreational use whereas dissolved metals are used for ecological assessments as this is the bioavailable fraction of the metal (the part that is toxic to organisms).

Metal in Water

NHMRC (2008)2

Sample (total acid-extractable metals)

Recreational Water Guidelines

(mg/L)

Water1

(mg/L)

Water2

(mg/L)

Water3

(mg/L)

Water4

(mg/L)

Water5

(mg/L)

Water6

(mg/L)

Aluminium

No value

4.1

0.88

2.1

0.73

1.9

1.4

Arsenic

0.07

0.005

0.004

0.005

0.004

0.006

0.005

Chromium

0.5

0.005

<0.001

0.002

<0.001

0.002

0.002

Cobalt

No value

0.0023

0.0006

0.0011

0.0008

0.0006

0.0005

Copper

20

0.0050

0.0026

0.0033

0.0017

0.0041

0.0091

Lead

0.1

0.0018

0.0004

0.0009

0.0004

0.0005

0.0004

Nickel

0.2

0.0071

0.0042

0.0054

0.0044

0.0040

0.0037

Zinc

30

0.009

0.002

0.004

0.002

0.003

0.003

2NHMRC (2008) Guidelines for managing risks in recreational waters (10 x drinking water guideline value, Table 9.3)

 

Metal in Water

ANZG 20183

Sample (dissolved metals)

Water Quality Guideline for aquatic ecosystems (95% species protection)

(mg/L)

Water1

(mg/L)

Water2

(mg/L)

Water3

(mg/L)

Water4

(mg/L)

Water5

(mg/L)

Water6

(mg/L)

Aluminium

0.055

<0.04

<0.04

<0.04

<0.04

<0.04

<0.04

Arsenic

0.013

0.004

0.004

0.005

0.004

0.006

0.005

Cadmium

0.0002

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Chromium

0.001

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

Cobalt

No value

0.0003

0.0003

0.0003

0.0006

0.0002

0.0001

Copper

0.0014

0.0025

0.0018

0.0019

0.0018

0.0016

0.0016

Lead

0.0034

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Manganese

1.9

<0.001

<0.001

0.008

0.073

<0.001

<0.001

Nickel

0.011

0.0037

0.0034

0.0037

0.0036

0.0028

0.0029

Selenium

0.011

<0.005

<0.005

<0.005

<0.005

<0.005

<0.005

Silver

0.0005

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

Zinc

0.008

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

3ANZG (2018). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia.