Coastal Connections & Estuary Updates

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Estuaries are the place where the freshwater from our catchments meet the saltwater of the sea.  

Glenelg Hopkins CMA collects readings and observations for the Hopkins, Merri, Yambuk, Fitzroy, Surry and Glenelg estuaries and compiles a snapshot of estuary condition. More detailed estuary profiling is conducted as well and can be seen via the links below.

Regular observation, measurement and evaluation of our waterways over time provides information on the health of our catchments. This information assists with the maintenance and rehabilitation of our waterways.

To receive the latest Coastal Connections or the latest Estuary Update, send your email details to: with Coastal Connections in the Subject Line or click here.

To see profiling for your local estuary, click on the estuary links below.







Constant monitoring of estuary condition is vital. Factors looked at when assessing an estuaries health are:

  • Depth
  • Temperature
  • Dissolved Oxygen (DO)
  • Turbidity
  • pH
  • Total Dissolved Solids (TDS)


Temperature of a water body directly affects many physical, biological and chemical characteristics.

Temperature directly affects the metabolic rate of plants and animals. Aquatic species have evolved to live in water of specific temperatures. If the water becomes colder or warmer, the organisms do not function as effectively, and become more susceptible to toxic wastes, parasites and diseases. With extreme temperature change, many organisms will die. Changes in long-term temperature average may cause differences in the species that are present in the ecosystem.

Dissolved Oxygen (DO)

Dissolved oxygen is a measure of the quantity of oxygen present in water. Oxygen is essential for almost all forms of life. Aquatic animals, plants and most bacteria need it for respiration (getting energy from food), as well as for some chemical reactions. The concentration of dissolved oxygen is an important indicator of the health of the aquatic ecosystem. Persistently low dissolved oxygen will harm most aquatic life because there will not be enough for them to use.
In some circumstances, water can contain too much oxygen and is said to be supersaturated with oxygen. This can be dangerous for fish. Supersaturated conditions occur in highly turbulent waters in turbines and at spillways, because of aeration, and also on sunny days in waters experiencing algal blooms or with many aquatic plants, because of photosynthesis. In this supersaturated environment, the oxygen concentration in fishes' blood rises. When the fish swim out into water that has less dissolved oxygen, bubbles of oxygen quickly form in their blood, harming the circulation.


In general, the more material that is suspended in water, the greater is the water's turbidity and the lower its clarity.
Suspended material can be particles of clay, silt, sand, algae, plankton, micro-organisms and other substances. Turbidity affects how far light can penetrate into the water. It is not related to water colour: tannin-rich waters that flow through peaty areas are highly coloured but are usually clear, with very low turbidity. Measures of turbidity are not measures of the concentration, type or size of particles present, though turbidity is often used as an indicator of the total amount of material suspended in the water (called total suspended solids). Turbidity can indicate the presence of sediment that has run off from construction, agricultural practices, logging or industrial discharges.


pH is a measure of acidity (or alkalinity). Pure water has a pH of 7, acidic solutions have lower pH values and alkaline solutions have higher values. Values of pH range from 0 (highly acidic) to 14 (highly alkaline). Where water has no net alkalinity or acidity it is said to be neutral and has a pH of 7.

Total Dissolved Solids (TDS)

TDS is a measurement of all suspended organic and inorganic solids smaller than 2 micrometres (μm) within a solution. Although an important parameter, TDS is not a direct indication of water quality, especially when dealing with estuarine or marine waters. TDS is more commonly used in freshwater streams, lakes and reservoirs where the water is intended for consumption. It is related to more aesthetic characteristics such as colour and clarity; characteristics that may affect potability. Total dissolved solids can be leached from stormwater runoff and agricultural runoff but are also found naturally leaching from rocks within soils. Values below 500mg/L are usually acceptable for human consumption.


Help find Percy a home

The ‘Big Fish Hotel Project' has a new face for the campaign - Percy the Estuary Perch.

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Have your say about our estuaries

The southwest community are invited to have their say at the Hopkins & Merri Estuary Management Plan Review Workshop in Warrnambool.

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New digs for Merri River fish

Fish in the Merri River are in for a treat, with six fish hotels set to be established in theMerri River estuary.

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Grants available to protect Vic Coasts

Community organisations have been called on from Minister for Environment, Climate Change and Water The Hon Lisa Neville to apply for grants up to $7500 for projects that assist in protecting and enhancing the coastal and near-shore marine environment in the Barwon South West region.

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