THE NSW Environment Protection Authority has issued Central Coast Council an official caution over the alleged breach of its sand dredging licence for The Entrance channel.
Last year, the council had been dredging sand from the channel and discharging it to replenish North Entrance Beach.
In December, the EPA served council a prevention notice to stop the discharge of sediment waters dredged from the channel onto the beach.
A spokesperson for the EPA said council had breached its licence, a claim the council disputed.
"Council has been told that dredge slurry must pass through an appropriate pollution control system for treatment, prior to discharge," the EPA spokesperson said.
"Dredge slurry can contain pollutants such as oil sludge as well as rocks and other debris which can accumulate in the channel."
Central Coast Council said it was continuing to work with the EPA and state government to "assess the allegations made in the prevention notice".
A spokesperson for the council said the prevention notice was issued after the council had completed 95 per cent of its scheduled dredging for the year.
"Council successfully moved 45,000 cubic metres of sand from The Entrance channel as part of the 2018 dredging program," the spokesperson said.
Cutting the dredging short did not have a significant impact on the estuary, they said.
"The incompletion of the previous dredging program has not had any identifiable adverse impacts to the health of the estuary. Estuary health is mainly affected by water quality from stormwater running into the lakes from the catchment," the spokesperson said.
"The channel shape is always changing and is currently in a typical condition for this time of the year."
Council continually monitored Tuggerah Lakes and The Entrance channel to ensure an exchange of water between the ocean and the lake continued to occur, which it was, the spokesperson said.
"Like many other coastal lakes and lagoons in NSW, Tuggerah Lakes is classified as an intermittently closed and open lakes or lagoon (ICOLL) and naturally alternates between being open and closed to the ocean.
"ICOLLs are separated from the ocean by a highly dynamic sand beach barrier or berm which is constantly influenced by the movement and redistribution of sand and sediments by waves, tides, flood flows and winds."
The spokesperson said council had a number of strict licence conditions in place which ensured the local environment and community were protected.
No dredging was scheduled for the immediate future, they said.
The former Wyong Shire Council has dredged The Entrance channel when needed since 1993.
The EPA this week said Central Coast Council had been given a deadline to respond to an EPA request.
"The EPA has also told council to inform the EPA by October 4 whether it intends to hold a licence for this [dredging discharge] activity. Irrespective of a licence for the activity, the requirements for environmental protections remain the same," they said.