Bellingen Riverwatch data results supports the findings from the Bellinger and Kalang River Eco Health Report Card (2011) and the Bellinger River Health Plan (2010) and tells us that there are elevated nutrient levels in the river, particularly phosphate, and low Dissolved Oxygen levels. Phosphorus is a naturally occurring nutrient that originates from plant and animal matter, and is applied as fertilizer to increase plant growth in agriculture. Dissolved oxygen is a measure of the availability of oxygen to aquatic life. The amount of oxygen in the water regulates the distribution, activity, movement, and behavior of all aquatic animals.
From Bellingen Riverwatch data to date, we can see elevated Available Phosphate levels presenting in the Upper Bellinger River, Upper Kalang River, Upper Never Never River and Rosewood River. Low Dissolved Oxygen levels are presenting at sites in the Upper Bellinger River, on the Rosewood RIver and Spicketts Creek, and at all of our testing sites on the Kalang River and Never Never River. In the Bellinger and Kalang River Eco Health Report Card (2011), the Bellinger River received a B- mark, and the Kalang River received a C+ mark.
When interpreting data, we have used the ANZECC Water Quality Guidelines for a healthy lowlands river system. The graphs below show the Dissolved Oxygen and Available Phosphates data across the Bellinger and Kalang catchments July 2017 to March 2019. A current data spreadsheet with our raw data to date is available here.
How to read our graphs
We have used a box and whisker plot to represent the complete data set from July 2017 to present. This plot style is commonly used to show key parameters regarding data sets. The maximum and minimum are represented via the whiskers and the box is showing average data and the median.
To improve legibility of our data, we have removed outliers. Outliers have been removed by determining the midpoint in the upper and lower quartiles, to define the upper and lower bounds of the data. Data outside these bounds has been removed to create the graphs below.
Phosphates are the essential plant and animal nutrient that occurs naturally in very low levels in Australian soils. The ANZECC Water Quality Trigger Values for Available Phosphates for moderately disturbed ecosystems for Lowland Rivers is 0.02mg/L.
The graph below shows the Available Phosphate data across the Bellinger River, Kalang River, Never Never River, Rosewood River and Spicketts Creek from July 2017 to present.
Sites that are regularly failing to meet ANZECC guidelines for a Healthy River System for Available Phosphates are B2, B2.1, B3, B4, B6, K1.2, R1 and S1.
Frequent occurrence of results above 0.02mg/L could be harmful to aquatic ecosystems and increases the likelihood of impacts on waterways such as an abundance of algae and aquatic weeds which out-compete native plants; waterways choked with vegetation; increased biochemical oxygen demand; reduced dissolved oxygen; reduced plant and animal diversity; blue-green algal blooms; and eutrophication.
Possible causes of results outside these values include agricultural fertilisers, sewage, sediments from erosion, faeces from feedlots, dairies and pets, phosphate-based detergents, decaying plant material and industrial waste.
Scientists from the NSW Office of Environment and Heritage are carrying out a comprehensive bi-annual water quality and macroinvertebrate surveys (reports due early 2019) which will help identify the causes of elevated phosphate and nitrate levels.
The ANZECC Water Quality Values for Dissolved Oxygen for moderately disturbed ecosystems for Lowland Rivers (less than 150m elevation) is between 85% and 110% saturation.
The graph below shows the Dissolved Oxygen data across the Bellinger River, Kalang River, Never Never River, Rosewood River and Spicketts Creek from July 2017 to present.
Sites that are regularly failing to meet ANZECC Guidelines for a healthy river system for Dissolved Oxygen are B1, B2.1, B4, K1, K1.1, K1.2, K2, K3, K4, NN1, NN1.1, NN1.2, NN1.3, NN2, and S1.
Results outside the guidelines could be harmful to ecosystems. Anything below 85% is a threat to aquatic life and the macroinvertebrates that our turtles love to eat. Potential impacts outside ANZECC trigger values include lack of oxygen to support aquatic plant and animal life and fish kills.
Monitoring Dissolved Oxygen levels is very important as the Bellingen River Snapping Turtle (BRST) is able to supplement its oxygen uptake through cloacal (bum) breathing, reducing its need to come to the water surface to breathe.
Possible causes of reduced oxygen levels in the river include low flow, stagnant water, organic waste such as sewage, fertiliser run-off and excessive algal growth in the waterway. Micro-organisms use the oxygen as they break down the organic matter.
Our current raw data spreadsheet is available here.