A core element of the Drought Resilient Pasture Landscapes project (2022-2024) was a coaching program to develop producers’ skills and knowledge in: pasture assessment, setting herbage mass targets to maximise pasture productivity and the health of agricultural ecosystems, feed budgeting, and using climate forecasts in the feed budgeting process. These practices ensure good ground cover and reduce rainfall runoff and the movement of soil and nutrients, contributing to the sustainability of regional landscapes, and complementing other practices such as revegetation of waterway areas.
As part of the project, participating landholders and experts from Dr Sarah Mika’s Aquatic Ecology and Restoration Research Group at the University of New England carried out extensive water monitoring, adding to the available data for four catchments.
Actively monitoring water health
This study was conducted as part of the Drought Resilient Pasture Landscapes project to assess water quality in a number of upland river systems. Eight sites were located across six rivers and four catchments (Figure 1). The western, or inland, draining rivers were Deepwater River and Macintyre River in the Border Rivers catchment, and Macdonald River in the Namoi River catchment. The eastern, or coastal, draining rivers were Mann River in the Clarence River catchment, and Gara River and Apsley River in the Macleay River catchment.
Figure 1 Location of water sampling sites at Clarence River, Macleay River, Border River and Namoi River Catchments, New South Wales, Australia
The aim of the study was to improve the knowledge of land managers of waterway health and to better understand the connections between pasture management and waterway health. Overall, sites were enriched in total nitrogen and total phosphorus, low in sediment load, and experienced periods of high water temperature and low oxygen saturation. While the amount of bioavailable nutrients was generally low at most sites, the pool of potential nutrient availability was high, suggesting a legacy of lingering nutrient addition. Careful management of phosphatic and nitrogenous fertiliser applications also remains an important component for the health of waterways so as to not further add to the existing nutrient load.
With the exception of a few outlier points, sites were similar to each other. Current land use practices will have an impact on water quality and nutrient loads, but historic land use has a long-lasting legacy effect. For example, the periods of high water temperature and low oxygen saturation are likely a legacy from the large-scale removal of vegetation that has removed overstory plant communities from providing shade to water surfaces. The low level of sediment load observed at all sites is suggestive of good ground cover and adequate level of herbage mass, which combine to reduce rainfall runoff and soil erosion and loss.
Restoring and protecting riparian vegetation and good management of pasture landscapes improves river health, and increases river resilience. Riparian vegetation and pastures with good ground cover and adequate herbage mass reduce erosion, and minimise and trap sediment and nutrients from land run-off, limiting the amount of new pollutants entering the river. Riparian vegetation also significantly reduces summer water temperatures compared to streams that have no shading. An important step in restoring riparian vegetation is preventing further vegetation loss or damage to restoration efforts by controlling stock access as appropriate.
You can download a low-res version of the full report here (3.6mb PDF) or use the Contact Form to request a high-res version.
Glossary of terms used to describe water quality
What is temperature?
Temperature is a measure of heat and cold. Temperature is measured in degrees Celsius (°C).
Why is it important?
- related to oxygen in the water
- if water gets too hot there is less available oxygen for living things
- affects the metabolic rate of aquatic animals, rates of development, breeding cycles, mobility, migration patterns
- affects the sensitivity of organisms to toxins, parasites and disease.
Things that impact water temperature
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What is Dissolved Oxygen?
Dissolved oxygen (DO) is the volume of oxygen that is contained in water.
Why is it important?
- DO is vital for the survival of fish and aquatic invertebrates
- prolonged exposure to low dissolved oxygen levels (<5 –6 mg/L) may not directly kill an organism but will increase its susceptibility to other environmental stresses.
- exposure to very low dissolved oxygen levels (<2 mg/L) will kill aquatic life and only the airbreathing organisms will remain.
Things that affect DO level in water
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Increases due to
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Decreases due to
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What is pH?
pH is a measure of the acidity or alkalinity of a substance.
Why is it important?
- The best pH level for most organisms in Australian waterways is pH 6.5 to pH 8.2.
- Changes in pH outside this normal range can cause a reduction in species diversity, with many of the more sensitive species disappearing.
Things that affect pH
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Source: Junior Waterwatch teachers’ Guide, Waterwatch NSW
What is electrical conductivity (Salinity)?
Electrical conductivity (EC) is the presence of salts like chlorides of sodium, magnesium, calcium, potassium and sulfates dissolved in water. EC is recorded in microsiemens per centimetre (μS/cm).
Why is it important?
- Increased salinity in water and land cause problems like salt scalds, inability to use saline water for irrigation, drinking, industry etc., damage roads, building foundation, high water treatment cost.
Things that affect EC
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What is turbidity?
Turbidity is the cloudiness or muddiness of water. Particles of clay, silt, sand, algae, plankton and other substances increase turbidity.
Why is it important?
Increased turbidity can affect:
- how much light can penetrate the water, reducing plant growth and oxygen production
- breeding and survival of fish & other aquatic animals
- water temperature, because sediments absorb more sunlight, raising the temperature
- oxygen levels, which decrease as water temperature rises
- visual clarity of water
Things that affect turbidity
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What is available phosphate?
Phosphorus (P) is a nutrient essential to the growth of plants and animals. Available phosphate is a measurement of the phosphate compounds that are soluble in water and therefore available to be absorbed by plants.
Why is it important?
- Native vegetation (both aquatic and terrestrial) has adapted to low levels of phosphate found in Australian soil and rivers.
- High phosphate levels in water cause overabundance of algae and aquatic weeds.
- Decreases dissolved oxygen in water
- Native species are replaced by exotic species
Things that affect phosphate level in water
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What is Nitrogen?
Nitrogen (N) is a nutrient essential to the growth of plants and animals. Oxides of nitrogen (NOx) is one of the most common forms of nitrogen found in waterbodies that are available for uptake by plants.
Why is it important?
- if nitrogen and phosphorus concentrations are high, they can contribute to algal blooms and infestations of aquatic macrophytes.
- excessive algal and macrophyte growths can lead to clogging of waterways, and massive oxygen demand at the end of a bloom when the plant material is decaying (oxidising).
- these conditions result in the death of fish and aquatic macroinvertebrates.
Things that affect nitrogen level in water
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Handy resources
Water bug detective guide
https://www.nswwaterwatch.org.au/resources
Freshwater macroinvertebrates and where you might find them
https://www.nswwaterwatch.org.au/resources/water-bug-id-charts-and-posters