Quarterly results July to September 2024

In response to flooding events and fish deaths in March 2023, the NSW Environment Protection Authority (EPA), in partnership with the NSW Department of Climate Change, Energy, the Environment and Water (DCCEEW), is monitoring the health of the Darling-Baaka River.

This report provides the monitoring results between July and September 2024. Monthly water samples were collected from 34 sites (see map 1) and measured for:

  • temperature
  • dissolved oxygen
  • nutrients
  • PH
  • chlorophyll a
  • algae
  • metals (from 9 sites)
  • pesticides from sediment (15 sites)

Five automatic monitoring smart buoys recorded water quality every 30 minutes.

View the real-time data.

Guidelines used in this report

The South Central Australia guidelines of ANZECC, 2000 are used for this project. In the absence of chlorophyll-a measurements in these guidelines, South East-Australian guidelines (ANZECC 2000) have been used. For pesticides and metals, guideline values are the 95% species protection level (i.e. the level that protects 95% of species; ANZG, 2020).

Nutrients

Samples showed consistently high levels of total nitrogen (TN) and total phosphorous (TP). On average, TN and TP exceeded these guidelines by up to 1.5 and 3 times respectively (Table 1). High nutrients levels can lead to algal blooms and may be harmful to animals and humans.

Pesticides and Metals

All pesticide concentrations in sediment samples were below guideline values.  Concentrations of zinc and copper exceeded guideline values at sites 2, 9, 11, 12, 20, 22 and 29 (Table 1), with site 29 exceeding guidelines for copper only.

Algae

 

Algal levels were very high in the study area, with chlorophyll-a concentrations ranging from 20 to 130 µg/L. Chlorophyll-a concentrations are very high during this study period, exceeding the 5 µg/L guideline value.

Dissolved Oxygen

All dissolved oxygen (DO) levels recorded were within the recommended concentrations for biota (>4mg/L).

Overall assessment

The areas of concern for the current sample period were elevated nutrient, metals and chlorophyll levels. A summary of results is provided in the table below, with full results available for download.

Contact [email protected] for more information.

Table 1

Default guideline values for a 95% level of species protection for toxicants in freshwater ecosystems (ANZG, 2020).

Toxicant95% species protection guideline value
Copper1.4 µg/L
Zinc8 µg/L

 

Water quality summary

Date 1: 23 July – 1 August     Date 2:  8 August – 28 August     Date 3: 6 – 24 September

Sampling
site


 
Dissolved
oxygen
NutrientsPesticides*Metals
Date
1
Date
Date
3
Date
1
Date
2
Date
3
Date
Date
Date
Date
1
Date
2
Date
3
TNTPTNTPTNTP
S1   
 
 
S2    
S3       
 
 
S4      
 
S5       
 
 
S6        
S7         
S8        
 
 
S9     
S10    
 
 
 

 
S11    
S12    
S13    
 
 
S14    
 
 
S15          
 
 
S16       
 
 
S17        
S18 
 
  
 
 
S19    
 
  
 
 
S20        
S21    
 
 
S22       
S23     
S24    
S25    
 
 
S26       
 
 
S27 
 
     
 
 
S28       
 
 
S29       
S30       
 
 
S31       
 
 
B1    
 
 
B2    
 
 
B3    
 
 

   ​    Meets guidelines          ​      Outside of guidelines
Guidelines used are for lowland river ecosystems in South Central Australia (ANZECC 2000)

* Pesticide results are reported from sediment samples

Sample sites for the Darling-Baaka River health project July 2024 - September 2024