Fisheries officers from the NSW Department of Primary Industries (DPI) are concerned attempts to illegally open a coastal lake at Narooma could lead to large scale fish kills.
Investigations are underway following ongoing attempts to illegally open what are know as Intermittently Closed and Open Lakes and Lagoons (ICOLLS).
DPI Acting Director Fisheries Compliance, Brett Andrew, says fisheries officers have been alerted to several attempts to artificially open Little Lake, Narooma.
Little Lake is one of 70 estimated ICOLLS on the NSW coast.
“ICOLLs open and close to the ocean naturally in a constant but irregular cycle,” Mr Andrew says.
“Currently, the water level in Little Lake is high. This has caused concern for some lakefront property owners and local residents.
“When there is sufficient water flowing into the lake or lagoon from the catchment area – usually following heavy rainfall, water levels in the ICOLL will rise.
“Eventually the water in the ICOLL will spill over the entrance sand berm and drain to the ocean. The force of the backed up water then quickly scours an entrance channel through the beach and reopens the ICOLL to the ocean.”
Mr Andrew says ICOLLS close when the ocean waves and tides push sand from offshore into the entrance, which gradually closes the entrance channel. Without further large freshwater flows into the estuary from the catchment, the ICOLL will remain closed to the sea.
“Opening ICOLLs artificially without permit is illegal as it can lead to large scale fish kills caused by sudden drops in water levels and dissolved oxygen levels as well as increased exposure and death of aquatic vegetation which can cause odours,” he says.
“Most ICOLLs have existing opening protocols in place, these are developed after extensive consultation with council, the community and government agencies. They are designed to protect infrastructure and residents from flooding, while still protecting the unique environmental values of these systems.
“DPI Fisheries Compliance and Eurobodalla Shire Council are working together to repair the attempted illegal opening to mitigate any negative environmental impacts and investigations are underway to identify the person/s responsible.”
Where possible, ICOLLS are left to open naturally. Councils can get permission to artificially open an ICOLL if there is an existing pressure from flooding or to avoid the likely threat of flooding to infrastructure.
The Nature Coast Marine Group is one of those to raise the alarm around Little Lake.
“Illegal efforts over the past couple of weeks to open Little Lake at Narooma to the sea could have disastrous environmental consequences,” the group says on their Facebook page.
“Sure, individuals have varying ideas as to how lake closures and openings affect waterway health, but decisions should be left to those who have environmental expertise and understand the interests of the community as a whole, as well as the fish and other wildlife that may be affected.
“It’s only a couple of weeks since thousands of fish died in Byron Bay after the Council there opened a lagoon in response to public pressure. That should be sufficient evidence that things are usually more complicated than they might seem.”
The maximum penalty for carrying out dredging works, such as digging a channel to open an ICOLL without a permit is $110,000.
Reports of illegal ICOLL opening can be made via the DPI Fisheries website or the Fishers Watch Phoneline on 1800 043 536.