With the end of the busy summer holiday period, and the departure of migratory Little Terns from the Karangi sand spit, Central Coast Council will commence the next stage of works this month at The Entrance channel to ensure it is in an appropriate ‘flood ready’ state, by establishing a pilot channel.

Council currently monitors the channel condition in real time (via remote cameras, satellite imagery and gauges, that monitor tidal range within the estuary) and forecasts catchment inflows and lake heights. This allows early intervention at The Entrance channel if a flood event is expected.

Council’s Unit Manager Environmental Management Luke Sulkowski said the foreshores of Tuggerah Lakes, however, will always be flood prone, regardless of the channel configuration. 

“While currently we have not reached any of our established  triggers requiring Council to undertake work on The Entrance channel, we plan  to excavate sand from the lake side of the sand berm and to the north of the rock shelf as a pre-emptive action, given the forecast shift to La niña weather conditions.  This is in accordance with our procedures to reduce the time and effort required by Council work crews in the event of a flood and to ensure appropriate response actions are implemented faster for our community,” Mr Sulkowski said

Council’s main concerns with the current configuration of the channel are with its current tendency to track south between the rock shelf and The Entrance Beach groyne.

“This is an observation we have continued to see since construction of the groyne in 2017.  Prior to the construction of the groyne, even when constricted, the channel generally tended to flow to the north of the rock shelf.  With the channel tracking this far south, we have seen continued erosion to the southern foreshore of the channel and impacts to infrastructure including beach access points and The Entrance channel Lifeguard tower.  In this configuration the channel’s capacity to naturally widen and scour during flood is limited.”

Council understands the NSW Government, who constructed the groyne in late 2017, is currently reviewing the impacts of the groyne. 

“In the interim, from 20 February 2024, Council expects to spend about three days on site establishing a pilot channel to the north of the rock shelf,” Mr Sulkowski said.

The pilot channel will be 40-50 metres wide, and at a depth slightly above the current lake height.  To slow infilling due to natural processes, such as tides and wave run-up, and extend its usefulness, it will not be connected through to the ocean.  Whilst on site, remaining items that were installed to assist with the Little Tern breeding will also be removed .

“If a flood event occurs, and intervention triggers are activated, Council will then be able to connect the pilot channel to the ocean as lake levels rise and when there is sufficient hydraulic energy to establish flow. 

“It is important to understand that unlike our other coastal lagoons, the Tuggerah Lakes are very low, almost at sea level, and if a connected pilot channel were to be constructed now, it would not flow but instead result in almost immediate infilling with sand from the ocean due to dominant coastal processes.”

Mr Sulkowski noted that given the dynamic nature of our coastline and The Entrance channel, if it became apparent during the works program, there may be a need to make some modifications to the proposed program in order to ensure the most appropriate outcomes are achieved.

The planned works will be funded by Council as a flood preparedness measure, noting that the works are ineligible for funding under the NSW Government Boating Access Program.

Mr Sulkowski said although at times heavily constricted, the entrance to Tuggerah Lakes has not closed for over 30 years.

“Restriction at The Entrance Channel is a natural process, and benefits the health of the estuary.  The marginally higher lake levels that are retained during dry weather events allow for fringing wetland habitats to be inundated, and for better mixing to occur between the central lake basin and those areas closer to shore. This results in reduced wrack, algae and pollution impacts.”

Council Administrator Rik Hart said Council is acutely aware of the need to monitor the channel, hence Council’s investment in the technology used 24/7 to gauge tidal ranges. 

“The planned works this month are a part of this pro-active management of the channel,” Mr Hart said.

“However, Council encourages foreshore residents to be flood ready by understanding their local flood risk, planning for what to do if a flood occurs, getting their property ready, staying informed and looking out for each other.”

The works at The Entrance channel will commence on 20 February and be undertaken over a three-day period.

Further information is available at the following Council webpages

Flood risk tools | Central Coast Council (nsw.gov.au)

Types of flooding | Central Coast Council (nsw.gov.au)

Plan and prepare for an emergency | Central Coast Council (nsw.gov.au)