Healthy waterways and catchments are vital systems that keep our local towns and communities thriving and ensure a healthy and vibrant future.
Each year MidCoast Council teams up with experts from the NSW Department of Planning and Environment to investigate our local waterways. Water quality samples are taken across our six major catchments in order to learn more about how our waterways are doing, identify trends and cycles in our estuaries and help track the work being undertaken to protect them.
The result is the MidCoast Waterway and Catchment Report Card.
This year we shine the spotlight on how climate cycles and localised weather impact our estuary health, and the importance of strategic management of our waterways over the long term can help protect the social, economic, cultural and recreational values that our benefit our community.
View the 2022 Waterway and Catchment Report Card below
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What is the Report Card and why is it important?
Report Cards are an effective way to check on the health of our waterways. They help us compare current conditions with the condition we would like them to be.
Scientists use indicators to ‘health check’ our waterways. Just as your body temperature is used as an indicator that something may be wrong with your own health, indicators are used to show if something is out of balance or unhealthy in the system. The indicators are selected to assess the overall health or ecological condition.
The results of the Report Card are used to guide future management actions and ensure long-term ecological health of our catchments.
Report Card Grades
Report Card objectives
These objectives are specifically achieved by providing information to:
- Assist in the current and ongoing protection of “high conservation” areas that currently provide substantial water quality and biodiversity benefits to the rivers and estuaries.
- Guide and report on the remediation of areas that have high pollutant loads and highlight areas that may require further action.
- Help protect all waterways against further declines in water quality.
2022 waterway and catchment report card - summary
MANNING RIVER ESTUARY
The Mid and Lower Manning River Estuaries have remained in good ecological condition, while the Upper Manning Estuary improved from fair to good. There was a general decrease in water clarity across the entire system due to continuous inflow of sediments from the catchments.
Farquhar Inlet was open to the ocean all summer and while its grade remained good, there was a reduction in water clarity that was likely caused by resuspension of the sandy shoals due to wind and surf conditions.
The Dawson River Estuary saw a drop in grade from good to fair due to reduced water clarity and increased algal levels. Similar results were observed in Browns Creek which also scored a fair grade in its first summer of monitoring.
Two new sites were added in tributaries of the lower estuary, one in the upper Lansdowne River Estuary and one in Ghinni Ghinni Creek. The Lansdowne River Estuary scored an inaugural grade of fair due to issues with water clarity, while Ghinni Ghinni Creek was in good ecological condition with a comparatively clear water column.
The Khappinghat Estuary improved from fair to good condition this year due to a decrease in algal growth. Salinity levels in the estuary were very low reflecting another wet summer which resulted in water clarity remaining fair.
The estuary appears to be recovering from the impacts from the bushfires in 2019-20. Algal levels decreased possibly due to less nutrients in runoff the catchment due to regrowth of vegetation.
KARUAH RIVER ESTUARY
The grade for the Karuah River Estuary dropped to fair this year driven by a significant increase in algal growth. Large, localised algal blooms were recorded on most sampling occasions. The Branch Estuary retained its good grade as it didn’t experience the same increase in algal growth as the main estuary. However, there was a decrease in water clarity due to frequent runoff.
The grade for Myall Lake remained in excellent condition this year. Bombah Broadwater remained in good ecological condition despite a significant decrease in water clarity due to considerable runoff from the Myall River catchment.
The salinity of both systems was close to freshwater as a result of another very wet summer. For the first time in over a decade of monitoring, the average salinity was higher in Myall Lake than the Broadwater. This reflects the unique hydrology of Myall Lakes which have no major tributaries, only receiving runoff from the surrounding catchment.
Wallis Lake and Charlotte Bay both dropped from excellent to good this year due to higher algal growth during the summer.
Pipers Creek, Mid Wallamba and Coolongolook Estuaries retained their good grades. Water clarity was good but frequent runoff events delivered nutrients to the estuaries which fueled algal growth.
Wallamba Cove’s grade improved from fair to good, despite frequent runoff over summer. Nutrient levels in runoff remain a problem driving algal growth in the estuary.
Seagrass depth range was reduced at all sites in Wallis Lake as runoff from frequent rainfall restricted the depth to which seagrass can grow.
Good management of our lakes, rivers and estuaries requires understanding of how they work, predictions about future conditions and informed choice about actions to get the outcome the community wants.
MidCoast Council and Department of Planning and Environment (DPE) have worked together to put these principles into action.
International best practice suggests that research, modelling, management and monitoring should all use the measures of condition and success. DPE research allowed the development of a solid understanding of the impacts of catchment activities on lake health. It also concluded that abundance of algae and water clarity would be good indicators for the future.
Council used this scientific understanding to form the Water Quality Improvement Plan in 2009, which was designed to achieve a number of specific outcomes, expressed in terms of water clarity and algal abundance. Progress towards these outcomes has been measured using the same measures in the annual report cards.
The MidCoast Council community value the health of our waterways, and the Waterway and Catchment Report Card is a tool that Council use to monitor how we are tracking.
DPE have undertaken an ecological health monitoring program in Wallis Lake and Khappinghat as part of the state-wide Monitoring, Evaluation and Reporting Strategy (MER). As part of the strategy, these estuaries were selected as two of seven across the state to be sampled each year to track inter-annual variability in two ecological health indicators; chlorophyll a (the amount of algal growth in the water) and turbdity (the amount of sediment in the water).
Since 2011 the monitoring program has been expanded to cover other key sites across the MidCoast Council area. DPE have provided an independent scientific evaluation on the ecological health of Wallis Lake, Smiths Lake, Karuah River Estuary, Khappinghat and the Manning River Estuary.
In 2022 an additional three sites were added in the Manning River Estuary, following recommendations from the Manning River Estuary and Catchment Program.
Ecological health does not refer to environmental health issues such as drinking water quality, safety for swimming, heavy metal contamination, disease, bacteria, viruses or our ability to harvest shellfish or fish.
The monitoring program has assessed the Ecological health of Wallis and Myall Lakes, Manning and Karuah River Estuaries and the Khappinghat Estuary. There are a number of steps taken to determine the score for each zone and subsequent Report Card grade:
- Selecting the indicators.
- Identifying the guideline values
- Collecting the data.
- Calculating the zone score.
- Allocating the Report Card grade.
Selecting the indicators
Chlorophyll and turbidity were chosen as the indicators as they are proven to be very informative and responsive measures.
What we do on the land impacts on the quality of water that runs off. If the quality of the runoff is poor it puts stress on the environment. Stressors are changes to the environment that result from activity; these can lead to ecological harm. Stressors can include nutrients, acid leachate and sediment in the water (turbidity).
Ecological condition grades are a combination of turbidity (water clarity) and algae (measured as chlorophyll a) scores.
Using the guideline values
A healthy ecosystem has an expected range of diversity and function which supports the environmental values and community uses of the waterway. Water quality monitoring is used to determine if the environmental value of (healthy) aquatic ecosystems is being met. Indicators (e.g., chlorophyll, turbidity) are selected based on a potential issue (e.g., excessive algal growth, excessive sediment in the water) that may pose a risk to the environmental value (e.g., aquatic ecosystems) being assessed. Guideline values for indicators have been derived from extensive monitoring of different estuary types in New South Wales and are based on data from pristine (reference) sites.
Guideline values may be given as a threshold value or as a range of desirable values for the indicator. Where an indicator (e.g., chlorophyll concentration, turbidity) is below the threshold (guideline) value, the risk to the protection of the environmental value (aquatic ecosystem) is low. Where an indicator is higher than the threshold value there may be a risk that the environmental value will not be protected, and further investigation may be required to determine the cause of the exceedance of the guideline value.
Guideline values are specific to different estuary types (e.g., lake, river, lagoon, creek) which each have specific physical forms and characteristics. In this study, Wallis Lake, Pipers Creek, Charlotte Bay, Bombah Broadwater and Myall Lake Estuary were classified as ‘lakes’; Mid Wallamba Estuary, Karuah Estuary, Wallamba Cove, Dawson River Estuary, Lansdowne River Estuary, Ghinni Ghinni Creek, Farquhar Inlet, The Branch Estuary, Lower Myall Estuary and Upper, Mid and Lower Manning River Estuaries were classified as ‘river estuaries’ and Khappinghat Creek was classified as a ‘lagoon’. For river estuaries, guideline values for turbidity and chlorophyll change depending on the salinity of the system at the time of sampling (Table X). This is because turbidity and chlorophyll concentrations are affected by catchment runoff after rainfall as more nutrients and sediments enter the waterway.
Table X Revised Guideline Values for turbidity and chlorophyll in NSW lakes, lagoons and rivers (OEH 2018) derived from the 80th percentile of data collected at reference in the NSW estuary monitoring program.
River estuary (salinity >25psu)
River estuary (salinity 10-25psu)
River estuary (salinity <10psu)
Collecting the data
The MidCoast Council region has been divided up into six different reporting zones.
Samples were collected on six occasions between summer and autumn from November to April. This represents the part of the year when the highest chlorophyll concentrations are expected.
At each of the selected sites, samples were taken in accordance with the New South Wales Monitoring, Evaluation and Reporting protocols.
Allocating the Report Card Grade
Defining the Report Card grade is an important step in the development of the Report Card. The grade definitions below are linked to the environmental values outlined above and are structured to allow easy comparison between each system and over time.
It is important that the cut-off values for each grade reflect the condition of each zone in comparison to a broader scale of condition across all New South Wales estuaries (i.e. an ‘Excellent’ grade represents an excellent condition for a New South Wales estuary).
To assist with the derivation of cut-offs, scores were calculated for 130 zones across a wide range of New South Wales estuaries using the same triggers and worst expected values as the MidCoast analyses. Cut-offs were then defined as representing a percentage of the scores for the state.
For example, a zone score less than 0.07 defined the 20% of best zone scores in the state and this became our ‘Excellent’ grade. We did not use a score of 0 as ‘Excellent’ because, as a consequence of how the trigger values are calculated, we expect that even pristine reference sites will exceed trigger values 20% of the time.