Lake Cathie

Lake Cathie_800x500.jpg

Lake Cathie is an important conservation and recreational area in the Camden Haven area, and the second largest estuarine saltmarsh in New South Wales. Responsibility for the management of Lake Cathie is shared between Council and the NSW Government.

The estuarine system on the west side of the Ocean Drive Bridge is owned by NSW National Parks and Wildlife. The estuarine system to the east of Ocean Drive Bridge is owned by the NSW Department of Planning, Industry and Environment - Crown Lands. Most activity Council wish to undertake within the waterway require permission from these agencies.

Concerns relating to non-Council related issues should be directed to these agencies.

Who is responsible for the lake?

We are responsible for We aren't responsible for
  • Flood mitigation
  • Stormwater drainage
  • Community protection
  • Management and maintenance of some surrounding foreshore reserves including:
    • Lake Cathie Foreshore Reserve
    • Jabiru Reserve
    • Aqua Reserve (limited)

Public health-related issues or issues relating to:

  • Water quality, safety, colour or salinity
  • Odour
  • Mosquitoes
  • Fish kills or fish health
  • Ecology of the waterway
  • Pollution or acid sulphate soils.

Water quality and safety

While we aren’t responsible for water quality of Lake Cathie, we do undertake water quality and algal testing for forward planning purposes. If you have concerns about the quality of the water and want to find out if it is safe to swim or fish, contact NSW Health or NSW Fisheries.

It is recommended by NSW Health that you do not swim:

  • within 24 hours of heavy rain at ocean beaches
  • within three days of heavy rain in estuaries or rivers

From time to time NSW Health offers general health advice for users of recreational water bodies across NSW where there is potential for contamination to cause disease and illness in the community.  If a pollution incident should occur, we will advise the community via our news channels. 

Revive Lake Cathie operate a Remote Smart Water Quality Sensor Monitor in Lake Innes that measures water quality parameters. They also monitor results as part of the Waterwatch NSW program. 

The colour of the waterway usually turns a brown colour after the system is closed to the ocean for an extended period of time. This is caused by natural process and does not necessarily reflect a reduction in water quality. Regardless, Council does not currently have permission to undertake an artificial opening of Lake Cathie to address water quality concerns.

Iron floc events and water quality

Professor Scott Johnston from Southern Cross University presented a talk which summarises work completed in 2021 by scientists from Southern Cross University, investigating the longer-term geochemical impacts of the recent iron floc event(s) in Lake Cathie.

A recording of Prof. Johnston's talk has been made available to share the findings with the community. Tune in to learn how dropping water levels quickly can affect water quality. 

 

Council received funding by the NSW Government under the Bushfire Affected Coastal Waterways grants to investigate how the Lake Innes, Lake Cathie and Cathie Creek waterway and saltmarsh community has recovered since the 2019-2020 bushfire/drought event.  A report was completed by Soil Conservations Services (2023) to investigate these impacts. The report found that despite the combination of drought and the subsequent artificial entrance openings liberating vast quantities of acid and iron, all potential acid sulfate stores were not exhausted, with 91% of all total net acidity in the lakebed sediments remaining in an unoxidized sulfidic state, principally as pyrite. Soil Conservations Services (2023) stated that artificial entrance openings, the ICOLL, and in particular Lake Innes, could experience similar chronic iron floc and acidification events in the future.

Lake-Innes-ASS-Risk-and-Fe-cycling-model

A copy of the report can be found here(PDF, 31MB).

Illaroo Road

Over many years, we have been working with the community to explore a feasible option to manage the potential coastal erosion risk to private and public infrastructure at Illaroo Road. This has involved coastal hazard studies, options assessments, extensive community engagement and collaboration on our forward plans.

In 2021, we engaged Rhelm and Bluecoast to carry out a co-design process to develop a reasonable, feasible and achievable solution. The findings of the report were considered at the October 2022 Ordinary Council meeting.

Council unanimously resolved to:

  • Note the findings of the Illaroo Road coastal protection options review and co-design project undertaken by Rhelm and Bluecoast Consulting
  • Note that all coastal protection options identified remain available, including a high crested revetment wall, low crested revetment wall, artificial reef and groynes
  • Continue to progress short term mitigation measures for coastal erosion adjacent to Illaroo Road, including sand nourishment and stormwater protection measures and, undertake emergency works as necessary should damage to stormwater and road assets occur
  • Advise people who participated in the co-design process or made submissions to this process of Council’s determination and develop community information to keep the community informed.

We are committed to finding a sustainable long-term solution for the coastal erosion issue through the Coastal Management Plan, and to providing short term and emergency mitigation works to provide certainty that ongoing protection and access to properties will be maintained.

The results of the co-design project will be built on in the development of the Coastal Management Plan through broader community engagement.

View the final report and the associated attachments below.

Council completed emergency protection works around the stormwater outlet off the southern end of Illaroo Road in April 2023. The works involved upgrades to the stormwater outlet, the installation of over 50 four tonne rock bags, sand nourishment of the upper dune profile and revegetation works. The works provide addition protection to both stormwater and road infrastructure.

Council has a DA that allows dredging of lower Cathie Creek. In 2021, Council amended its DA to include a Coastal Hazard trigger. This allows Council to dredge material from lower Cathie Creek to nourish the beach adjacent to Illaroo Road. The nourishment of the depleted beach with dredged material provides additional short to medium term protection to public and private assets along Illaroo Road.

Water levels and opening strategy

Our opening strategy guides the decision making process with respect to opening Lake Cathie to the ocean. It aims to:

  • minimise adverse effects on the ecology of the area
  • minimise build-up of sand in the lake entrance
  • reduce impacts of flooding.

We follow a standard operating procedure that outlines our required actions to manage and mitigate flood risks once Lake Cathie reaches 1.6 metres AHD (Australia Height Datum). When water levels are at 1.6m, this is not the point that water inundates sewer infrastructure or resident's homes, but it is the point where we begin to closely monitor water levels.  Once Council water levels reach 1.6m AHD, Council monitors water levels at Lake Cathie twice daily.

To mitigate flood risks, Council have recently scraped the sand berm back to a level of 1.6m AHD. This aims to replicate a natural opening before water levels flood sewer infrastructure and was based on advice from the NSW Government. The 1.6m trigger level represents the point that our staff are able to mobilise and prepare to act should these certain conditions present. It does not automatically initiate our responsibility to scrape the berm. 

At this point, we start planning and mobilising to undertake works to allow water levels to reduce before it inundates sewer infrastructure and resident’s homes. Enacting flood mitigation measures also relies on other factors, including substantial rainfall confirmed on the long-term forecast, water levels continuing to rise, and optimum tidal conditions.

Dredging Strategy

Dredging involves removing marine sand from a designated area of lower Cathie Creek, east of the Ocean Drive Bridge, and requires permission from the state government in the form of a Crown License which must be applied for before each dredging project. Dredging is undertaken to improve the recreational capacity of the waterway and to nourish the beach adjacent to Illaroo Road, to provide additional protection to assets against coastal hazards.  The lake and sand West of Ocean Drive Bridge is owned by NSW National Parks, meaning Council is unable to dredge in this area.

In the years following dredging, sand accumulates into the lower estuary and can impact on the amenity of the recreational activities generally undertaken in the lower waterway. The sand buffer on Lighthouse Beach is typically also lost during this time due to the erosional nature of the beach environment.

This work is typically undertaken with a ‘suction/cutter' dredge. The beach nourishment work involves placement of dredged sand in front of the properties along Illaroo road to form an artificial dune. The placement of this sand is typically undertaken by an excavator with the sand being pumped to the beach via a pipe from the dredge.

You can read more about dredging in our Dredging Strategy.

Coastal Management Program (CMP)

We are in the process of preparing a Coastal Management Program (CMP) which aims to provide a long term, coordinated strategy for managing the coastal zone in accordance with the Coastal Management Act 2016 (CM Act) and local objectives. This management program will be implemented through coordination between ourselves, state agencies and other key stakeholders. For more information about the Coastal Management Program: Coastal Management Program Port Macquarie Hastings Council (nsw.gov.au)

Community Plan

The Lake Cathie Community Plan(PDF, 9MB) is a community-led, 5-10 year plan, which was developed through a partnership between Council and the community.

The plan:

  • highlights what is special and unique about the area
  • reflects community’s vision for the future
  • identifies key priorities and actions to achieve the community’s vision.

Unauthorised openings

Heavy penalties apply for members of the public who attempt to open Lake Cathie without approval.

Port Macquarie-Hastings Council is committed to long-term planning for Lake Innes and Lake Cathie, working with NSW Government agencies while also having protocols in place to manage potential flooding and to minimise environmental impacts.

Attempting to open Lake Cathie through the lake’s entrance sand-berm is an offence under several pieces of Legislation.

Government agencies with responsibilities under this legislation will take action against persons found to be digging, scraping, excavating, dredging or moving sand in an attempt to open the lake’s entrance without authorisation, which is located on Crown land.

Maximum penalties of $110,00 for an individual or $200,000 for a corporation apply to digging up or disturbing soils on Crown Land, under the Crown Land Management Act 2016 and Regulations. Maximum penalties of $110,000 for an individual and $220,000 for a corporation apply to carrying out dredging work on water land without a permit, under the Fisheries Management Act 1994 and Regulations.

Frequently asked questions

We have collated frequently asked questions about Lake Cathie, view as a PDF document(PDF, 624KB) .

We have also collated the Council's responses to Revive Lake Cathie's questions regarding dredging, mosquito monitoring, Kenwood Drive Bridge, low water levels, acid sulphate soils, marine life and fresh water sources. View the responses(PDF, 41KB) as a PDF document.