Waterways Report Card 2019 Results

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Grades for Myall Broadwater and Myall Lake improved from good condition to excellent this year. As the Myall Broadwater, and to some extent Myall Lake, is strongly influenced by runoff from the Myall River catchment, continuing dry conditions meant that there was little runoff during the sampling times, resulting in clear waters and small amounts of algae. The marked variability in condition swinging from good to poor and back again emphasises the role of inputs from the upper Myall River and the need to continue to reduce nutrients from land use activities in the catchment.
The Myall River Estuary upstream of Tea Gardens was in good ecological health, algae levels varied from moderate to good and water clarity was good. This area is usually strongly influenced by the condition of the outflow from the Broadwater, but with limited runoff from rainfall, waters moved by tides have a greater influence on water quality.

Grades for Wallis Lake and Pipers Creek were excellent this year and this was the case for both water clarity and algae. While water clarity in the Mid Wallamba Estuary was good, higher than desired algal growth from excess nutrients, clear water and low flows resulted in a poorer overall grade this year.
The Coolongolook Estuary continued to show significant algal growth but water clarity was generally acceptable. Higher levels of algal growth in Wallamba Cove shows it continues to be affected by stormwater runoff from Tuncurry.
The depth where seagrass is able to grow improved at most sites and was excellent in Wallis Lake, but remained poor in the Mid Wallamba Estuary.

The Karuah River and The Branch Estuaries continued to show signs of significantly impaired estuary health with much higher than desired algal growth. These grades reflect excess nutrients from catchment runoff, clear water and low flows in the catchment.
As with last year, there was no seagrass in the mid to upper reaches of the Karuah River Estuary, likely a consequence of past and present conditions.

Khappinghat Estuary was in good ecological condition. Algal growth was low but there continues to be poorer than expected water clarity leading to continuation of the good grade, rather than the excellent grade expected.

The Manning River Estuary maintained good overall ecological condition. Water clarity was excellent throughout the estuary, however algal levels continued to be excessive. The high algal levels reflect optimum growing conditions of clear warm water and abundant sunlight throughout the sampling period, which allowed the algae to utilise nutrient runoff from the catchment following summer storms.
The depth range where seagrass is able to grow increased in the reaches to an excellent grade, the best results seen so far. Seagrass depth reduced slightly in the mid reaches and remained poor. Seagrass disappeared from the upper reaches for the first time since sampling began.

Smiths Lake remained in excellent condition despite an extended dry period which resulted in a dramatic drop in lake levels. Low rainfall and little runoff resulted in clear waters and low nutrient inputs.

Healthy waterways and catchments are vital systems that keep our local towns and communities thriving, and ensure a healthy and vibrant future.

So how do we know how our waterways are faring? Have things improved? Where do we need to do more work?

Every year, MidCoast Council teams with experts from the Office of Environment and Heritage to investigate our local waterways. The result is the MidCoast Waterway and Catchment Report Card.

We work hard in partnering with communities right across the MidCoast, including businesses and landholders, on many projects that improve water quality and the Report Card results are something to be celebrated by everyone together!

 

In the weeks following the Report Card release, we're hosting a number of free hands-on community activities, so please join us for one or more of our “Explore with an Expert” events - visit the event tabs below and be sure to complete the online form for events that require bookings!

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 

The Report Card grades the health of the waterways in a similar way to school Report Cards, with a grade ranging from A (excellent) to F (very poor).

Report Card objectives

The objectives for the Report Card are:

  1. To report on ecological health.
  2. To track progress on management actions.

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.

 

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 Office of Environment and Heritage (OEH) 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. OEH 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.

OEH 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 algae) and turbidity (the amount of sediment).

Since 2011 the monitoring program has been expanded to cover other key sites across the MidCoast Council area. OEH have provided an independent scientific evaluation on the ecological health of Wallis Lake, Smiths Lake, Karuah River and Estuary, Myall Lake and the Bombah Broadwater in the Myall Lakes the Lower Myall River, Khappinghat and the Manning River Estuary.

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. 

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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:

  1. Selecting the indicators.
  2. Identifying the trigger levels.
  3. Collecting the data.
  4. Calculating the zone score.
  5. 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) scores.

Identifying the trigger levels

A healthy ecosystem refers to a system which has normal ranges of diversity and function. These ‘normal’ ranges have been established from extensive monitoring of estuaries across New South Wales.

A trigger value is the value which indicates that a variable is outside the ‘normal range’ and could trigger further investigation. In our context, we have used the trigger value to indicate conditions which are not desirable for continued waterway health.

A trigger value is specific to different types of estuary. In this study, Wallis Lake, Pipers Creek, Charlotte Bay, Bombah Broadwater and Myall Lake were all classified as ‘Lakes’, Wallamba River, Karuah Estuary,

Wallamba Cove, Branch Estuary, Lower Myall River and Upper, Mid and Lower Manning Estuary River were classified as a ‘River estuary’ and Khappinghat was classified as a ‘Creek estuary’.

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 December to March. 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.

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Rainfall results

The amount of rainfall that occurs around the period of sampling for the Report Card (September – March each year) influences the Report Card results.

If there is more rain, there is more runoff in the catchment resulting in greater quantities of sediment and nutrients entering our waterways.

In general, the sampling period in 2017/18 was very dry, except for a significant storm in March 2018. If it wasn’t for the March 2018 rainfall event then the rainfall between September 2017 and March 2018 would have been the lowest since 2007.

The total rainfall for the sampling period was slightly above the long term average but half of that fell in one month.

The extended dry period resulted in good water clarity due to the minimal amount of catchment runoff entering the estuary. At some sites chlorophyll-a concentrations (algae) increased during this time period, as the dissolved nutrients in the system and the abundant light would have provided suitable growing conditions.

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