Tuggerah Lakes Estuary is a unique environment rich in biodiversity. Over the years, the natural function and condition of the estuary has been influenced by many different human activities around the foreshores and throughout the catchment.
Land clearing and land use change, loss of important natural filters (streambank, wetland and saltmarsh vegetation), changed water flows, more pollutants, nutrients and sediment reaching the lakes, and extensive foreshore modifications have all contributed to change – fewer native seagrass beds, more frequent algal blooms, increased amounts of smelly ‘ooze’ around the foreshores and an overall loss of habitat and amenity value for native plants, wildlife and the community.
Development pressure in the Tuggerah Lakes Estuary catchment grew rapidly from the 1960s onward as the area shifted from a holiday destination to a place of permanent residency, supporting ever-expanding residential, commercial and industrial centres.
Management of the wider catchment has improved with greater controls on farming, sewerage management and development.
Understanding the Hydrodynamics:
To fully appreciate the reasoning behind our management practices, it’s important to understand the unique hydrodynamics of the estuary. This system is classified as a perched estuary, meaning the water level in the three lagoons is, on average, above water levels in the open sea, with water levels maintained by sand berms. In addition, the three lagoons are very shallow, with an average depth of just 1.7 meters—much shallower than other nearby estuaries like Lake Macquarie, which averages about 8 meters.
This unique combination of being perched and shallow means that the sand berm that naturally forms across The Entrance plays an essential role in maintaining the balance of the system. During dry periods, the berm acts as a natural barrier, preventing water from draining out of the estuary. If the channel were kept permanently wide-open, we would risk a net loss of water, exposing mudflats and harming the overall water quality and ecosystem health. By allowing the berm to fulfil its natural function, and intervening strategically when necessary, we aim to protect the estuary’s health and mitigate flood risks.
Managing The Entrance Channel:
Council implemented the Interim Entrance Management Procedure in 2022. This procedure is guided by a set of advanced flood prediction tools and is designed to help us manage the entrance most effectively. The procedure is informed by a range of predictive tools, including the Manly Hydraulics Laboratory Flood Intelligence Tool (MHLFIT), which provides forecasts for water levels based on predicted rainfall. This allows us to predict lake levels up to four days in advance and take proactive steps to prevent flooding. Additionally, we monitor the constriction of The Entrance Channel using a range of measurements, including a gauge at The Entrance Bridge, to assess the impact of ocean tides on lake levels. This allows us to identify when intervention is necessary and ensure that any actions taken are effective.
However, due to the dynamic and natural processes at play in The Entrance Channel, regular, ongoing entrance works are not always feasible or effective. The constant natural movement of sand at the sand berm and channel infilling processes often quickly reverse mechanical entrance management works. We must therefore be very careful in our timing of optional non-flood entrance management works, which are carefully evaluated and executed when necessary. Modelling and experience have shown that these actions can help marginally reduce the peak water levels during a large flood, however no amount of intervention will ever eliminate flooding in low lying foreshore areas.
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Because we have a huge 700 square kilometre area of catchment land funnelling rainwater into just 80 square kilometres of estuary, no amount of intervention can ever fully eliminate flooding in the low-lysing floodplain areas around the estuary. On the plus side, allowing the water level to rise occasionally is actually essential for the health of the ecosystem. It deposits things like dead seagrass leaves up onto high, dry ground, waters important saltmarsh plants and replenishes our crucial wetlands.
Tuggerah Lakes is normally in the range of about 0.2m AHD to 0.4m AHD. Generally, if there is about 200mm of rain then the lake level can slowly rise over about three or four days to a minor flood level of 1.3m AHD. With about 350mm of rain, the lake water level can rise gradually over three to four days and result in major flooding of 1.6m AHD.
The minor flood level for Tuggerah Lakes is 0.9m AHD, which is the level at which some roads start to be flooded. Statistically there is about a 50% chance of at least this level of flooding each year. Over the past 100 years there has been flooding in the lake up to 2.1m AHD (in June 1949); there have been six floods higher than 1.7m AHD, including the July 2022 flood, which was the sixth highest at 1.72m AHD.
Council estimates that the largest flood that could conceivably occur – called the Probable Maximum Flood – could reach 2.7m AHD. This also happens to be the minimum floor level that Council has been setting for habitable areas of residential buildings around the lake over the past 40 years.
Computer modelling tools are available if you are interested in looking at the likelihood of different sizes of floods and their consequences. Council's region-wide online mapping tool, provides a range of flood information on a visual map. Please refer to the fact sheet on definitions of flood mapping layers for further details.
Unlike the coastal lagoons, which are predominately closed, Tuggerah Lakes is predominately open (the last time it completely closed was in 1987). If there is likely to be a flood in Tuggerah Lakes, then Council has an adopted procedure to help sand at The Entrance Channel to be better able to scour away so that the channel can gradually widen to let out more floodwater.
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Yes. One of the features that make Tuggerah Lakes Estuary so unique and sensitive is its perched elevation, meaning the average height of water in the lagoons is greater than the average height of water in the ocean. The reason this is possible is thanks to the sand berm that accumulates across the mouth of The Entrance channel. This is an example of nature’s incredible, natural engineering: The sand is strong enough to retain water during dry times, yet soft enough to wash away during a flood once enough pressure builds.
It's also important to understand that Tuggerah Lakes is a VERY shallow estuary, averaging only 1.7m in depth. To give that some context, our closest neighbour Lake Macquarie averages 8m in depth. If this sand berm wasn’t here, water would drain out to sea during dry and normal times, and that would make our shallow estuary even more shallow. This would result in decreased water quality and could expose mudflats for hundreds of meters.
Natural variations in the height of the water within Tuggerah Lakes supports the health of the estuary and can improve water quality. The higher water levels immerse the lake’s fringing wetland habitats, assist with the distribution of wrack and improve mixing of the water between shallow nearshore areas and deeper parts of the lakes. The fluctuations in lake levels also help to free and lift wrack that can get trapped near the shoreline and place it in areas where it can aerobically break down (such as saltmarshes, fringing wetlands, and foreshore reserve areas), reducing odour.
View our wrack management video for visualisations of this process.
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Council uses the Manly Hydraulics Laboratory Flood Intelligence Tool (MHLFIT)to help guide when Council intervention is required in order to mitigate the risk of flooding. Council also uses a gauge at The Entrance Bridge to provide a quantifiable measure of the influence of ocean tides on the estuary, and subsequently how constricted the channel is.
Our coastal lagoons, (Wamberal, Terrigal, Cockrone and Avoca) are opened if they are closed when water levels reach a trigger lpoint. This is a similar approach to that taken in other coastal local government areas. See our coastal lagoon web page for more information, current lagoon water levels and trigger levels.
For Tuggerah Lakes, our procedure is more unique and complex. Unlike the other coastal lagoons, Council may intervene in its management of the channel before it is closed and when water levels are predicted rather than reached.
MHLFIT uses Bureau of Meteorology predicted rainfall data to forecast potential lake levels up to four days before they occur, so Council intervenes at an earlier point in the process. This management approach is documented in the Tuggerah Lakes Interim Entrance Management Procedure – which prescribes actions to be undertaken that are tailored to different entrance conditions. Works may include berm scraping (reducing the height of the sand), pilot channels (creating a narrow channel with heavy machinery to create a second opening that will naturally widen) and emergency openings (in the unlikely situation of a completely closed channel).
At the request of community members and the Catchments to Coast Advisory Committee, an additional intervention trigger was endorsed as part of the Interim Entrance Management Procedure and Resolved by Council at the 14 December 2022 Ordinary Council meeting. In addition to the relevant response being triggered if Council’s Flood Intelligence Tools predict a flood level of 1.3m AHD or greater in Tuggerah Lakes (up to four days before they occur using conservative rainfall forecasts), it may also now be triggered if a measured water level of 7mAHD at the Yarramalong Water NSW gauge (211014) and 6mAHD at the Ourimbah Creek Water NSW (211013) gauge is recorded concurrently.
Council’s procedure for managing The Entrance Channel can be found within the Tuggerah Lakes Entrance Management Study.
Council is currently working towards the development of an Entrance Management Strategy through the Tuggerah Lakes Coastal Management Program. Interested community members can register their interest in staying up to date with news and opportunities to be involved.
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Central Coast Council engaged NSW Government’s professional specialist advisor, Manly Hydraulics Laboratory, to undertake the Tuggerah Lakes Entrance Management Study which was completed in August 2022. The project developed an evidence-based Interim Entrance Management Procedure for Tuggerah Lakes to reduce the risk to life, public and private infrastructure and public health.
The Interim Entrance Management Procedure is supported by flood intelligence tools that provide real-time predictive lake level modelling and data to ensure a proactive, informed and consistent response by Council when flood events are predicted.
The Interim Entrance Management Procedure is intended to guide Council’s channel management until the Entrance Management Strategy is completed through the Tuggerah Lakes Coastal Management Program. This process will provide opportunities for the community to get involved and have their say, as well as allowing all the social, economic and environmental factors to also be considered in deciding how we manage one of our greatest natural and recreational assets into the future.
Previously, following the release of Angus Gordon’s independent report, Review of Central Coast Council’s Lagoon and Lake Entrance Management, Policies and Practices, Council released the Tuggerah Lakes Entrance Management Study: Stage 1 Review of Previous Studies report as recommended.
The Stage 1 report includes a summary of over 20 studies from 1987 to present relevant to entrance management at Tuggerah Lakes. The report provides key background information and conceptual models to assist in understanding the complex nature of entrance processes and management at Tuggerah Lakes. Findings from the review are informing subsequent stages of the project and these will involve detailed modelling and consideration of the environmental, economic and social impacts.
View the complete Tuggerah Lakes Entrance Management Study for more information.
View the Interim Entrance Management Procedure for more information.
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The Tuggerah Lakes Estuary Management Plan (TLEMP) was adopted by the former Wyong Shire Council in 2006. The TLEMP was developed over a nine-year period and provides strategic direction for the management of the Tuggerah Lakes estuary and its catchment. It will soon be replaced by the new Tuggerah Lakes Coastal Management Program which is currently being developed.
The TLEMP incorporates the social, economic and environmental values of Tuggerah Lakes Estuary and was subject to community consultation before it was finalised and implementation began. It provides guidance on the types of actions that should be undertaken to protect the estuary, the order in which they should be completed and the estimated cost.
The overarching aims of the TLEMP are to ensure that:
- the quality and quantity of water meet the needs of the community and lakes and rivers
- the plants along the banks of rivers, lakes and in wetlands are protected because these are essential to a healthy ecosystem
- biodiversity and ecological integrity of the lakes ecosystem are maintained or enhanced
- human activities can take place while protecting cultural heritage and enhancing soil, water and ecosystem health
- the social and economic needs of the community are met while protecting the environment of the coastal zone
- we continue to improve our understanding of how the estuary works and incorporate this knowledge into management.
Snapshot of the Tuggerah Lakes Estuary Management Plan – Part 1
Snapshot of the Tuggerah Lakes Estuary Management – Part 2
Tuggerah Lakes Estuary Management Plan Part 1
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The Tuggerah Lakes Estuary Management Plan (TLEMP) is the current certified Coastal Zone Management Plan which aims to rehabilitate the Tuggerah Lakes estuary and its catchment to support ongoing health and vitality and protect against future impacts.
Since 2008, the Australian Government has provided $30.95 million in grant funding to assist with implementation of various aspects of the plan:
2008-2013: $20 million Australian Government Caring for our Country grant
2004-17: $3.25 million Australian Government National Landcare Programmes grant
2017-20: $3 million Australian Government Improving Your Local Parks and Environment grant
2020-23: $4.7 million Australian Government Environment Restoration Fund grant.
Council produced a video which outlined the science behind the estuary including estuary processes, water quality, human impacts, funding and future management of Tuggerah Lakes.
What has been done?
The Tuggerah Lakes Estuary Management Plan included four action plans relating to water quality, ecology, socio-economic values and knowledge and management. These action plans included 100 individual actions, of which 86% have been completed or are ongoing.
By working with our project partners and the local community, the following key achievements have been completed so far:- 40km rural stream rehabilitation
- 13km urban stream rehabilitation
- 2.5ha saltmarsh reconstruction
- 29ha saltmarsh rehabilitation
- 374ha wetland conservation and restoration
- 277 gross pollutant traps
- 37 constructed wetlands
- 29km of shared pathway
- 32 boat ramps & jetties
- 4 foreshore beaches
- Ongoing financial support for Environmental Groups (formerly Landcare)
- Award winning community education program
- Long term water quality improvement at multiple locations
- Extensive research & innovation to improve future management
View the Tuggerah Lakes Estuary Management Plan: Implementation Report 2008-20 for more information or view a shorter summary here.
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In accordance with the NSW Coastal Management Framework, Central Coast Council is required to develop new Coastal Management Programs (CMPs) for our part of the NSW Coast (excluding National Parks estate). These new management programs for each waterway will be valid for 10 years and will replace previous management plans. The process of re-doing these programs every 10 years is not only a NSW State Government requirement, but something we believe is important to ensure our projects reflect the latest advances in technology and ecology, and account for changes in the pressures and desires of our community.
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The Stage One Scoping Study has been completed and is now available – read online here. The Scoping Study provides a useful guide for Council and state government to work together to achieve the strategy, vision and objectives for Tuggerah Lakes. It includes a summary of the strategic, environmental, heritage and future contexts, identifies the purpose and maps out a series of forward planning tasks to fill key knowledge gaps. It also provides important information such as risk assessments to prioritise key issues and threats which will allow Council to establish an effective and implementable management program.
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An independent expert panel was appointed by the NSW Minister for the Environment to prepare a report on water quality in the Tuggerah Lakes Estuary. The information reviewed and incorporated within the report was prioritised based on input and feedback provided by the community, business and government stakeholders. The input focused the review towards (i) how the entrance influences water quality in the lake system, (ii) the water quality and ecological characteristics of the lakes themselves, and (iii) the influence of the adjacent catchment on the lakes’ water quality. The findings within the report are based on available scientific information, input from local stakeholders, the expertise of the members of the expert panel, and an understanding of the current and future pressures.
- View the full report online: Tuggerah Lakes Expert Panel Report
- View the Tuggerah Lakes Expert Panel Recommendations
- Read about our progress of implementing the recommendations: Tuggerah Lakes TLEP Progress Report
A series of webinars were held with members of the Tuggerah Lakes Expert Panel to explain the findings of their report.
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Tuggerah Lakes Estuary Management Study 2001-2004
The Tuggerah Lakes Estuary Management Study builds on the knowledge of the Tuggerah Lakes detailed in the Estuary Processes Study and details key issues and management options for improving the health of the Tuggerah Lakes estuary and its catchment. The study looks at options for areas such as stormwater management, saltmarsh rehabilitation, water quality, the channel, dredging and many others. The study contains input from a Community Reference Panel (including boating, fishing, environment, Aboriginal peoples, Dunecare and other representatives), as well as technical experts and local business organisations.
Estuary Management Study
Tuggerah Lakes Estuary Management Study Summary
Tuggerah Lakes Estuary Management Study full document inside cover
Tuggerah Lakes Estuary Management Study Part 1
Tuggerah Lakes Estuary Management Study Part 2
Tuggerah Lakes Estuary Management Study Part 3
Tuggerah Lakes Estuary Management Study Part 4
Tuggerah Lakes Estuary Management Study Part 5
Tuggerah Lakes Estuary Processes Study 1998-2000
Prior to developing management actions for the Tuggerah Lakes estuary, an Estuary Process Study was developed to outline the current environmental condition of the system and establish a ‘baseline’ from which to work. This involved looking at all the existing scientific studies and the completion of further studies covering many of the ecological processes of the lakes. Research looked at characteristics such as water quality, saltmarsh and seagrass habitats, sediments and their movement and stormwater. Written by Council staff and State Government agencies, the Process Study was hailed “the best in the state” by scientists who reviewed it