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Water levels and algal testing

Is it safe to swim?

It is recommended by NSW Health that users do not swim within 24 hours of heavy rain at ocean beaches and within 3 days in estuaries or rivers.  From time to time NSW Health does offer general health advice for users of recreational waterbodies across NSW where there is potential for contamination to cause disease and illness in the community.

If you have concerns about the quality of the water and want to know if it is safe to swim or for fishing contact NSW Health (North Coast Public Health Unit on 02 6588 2750) and NSW Fisheries . If a pollution incident should occur Council will take action and let the community know via our news channels.

In addition users may also like to refer to the land manager NSW National Parks and Wildlife Service (NPWS) alerts for Lake Innes Nature Reserve.

Water levels

The NSW Government uses automatic equipment to track Lake Cathie water levels. Follow the water level information here noting results are in AHD datum:  Manly Hydraulics Water Level Reporting

There are two different height datum’s used when referencing the lake level and the tidal level.  The lake levels, and those reflected on the Manly Hydraulics (MHL) site (the monitoring undertaken for NSW Government) are recorded against the Australian Height Datum (AHD). This datum point is commonly used to measure land levels but is also used to record water levels. AHD is based on mean sea level (i.e. the middle of the tidal range) and so 0.0m AHD is Mean Sea Level.

The ocean tide levels are recorded against a different datum, which is established on the Lowest Astronomical Tide (LAT). The difference between the lake level recorded on the Manly Hydraulics site and the corresponding ocean level commonly referenced in “tidal charts” is easily explained by the difference between these two datum’s. For reference, 0.0m LAT is actually 0.9m lower than AHD.

Water quality and algal testing

Council undertakes water quality and algal testing within the system for forward planning purposes only. If you have concerns about the quality of the water and want to find out if it is safe to swim or for fishing contact NSW Health or NSW Fisheries .

The monitoring Council does for water quality and algal presence is done as part of our role in managing the land surrounding the lake which includes the public reserve.  Testing results are available in the documents below.  We also monitor water levels for the purpose of protecting public infrastructure and property in circumstances relating to possible flood impacts.

Revive Lake Cathie and the NSW Department of Planning, Industry and Environment (DPIE) – National Parks & Wildlife have installed a Remote Smart Water Quality Sensor Monitor in the Lake Innes Nature Reserve. Water quality parameters are available on the Remote Smart Water Quality Sensor Monitor dashboard.

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This page was last updated on: 09 June 2021