A multi-million dollar sand transfer system designed to repair erosion on Jimmys Beach at Hawks Nest could be inadvertently contributing to the siltation of the Myall River mouth.
A horizontal sand bar has formed across the river's entrance in recent months at the same time as heavy seas have gnawed away at the beachfront, two kilometres away.
It has become particularly noticeable in recent days following last weekend's swell.
"The river hasn't cleared up since the March floods, which means it isn't flushing properly," Myall River Action Group spokesman Gordon Grainger said.
"It won't take long before it is completely closed over."
The river's ability to flush effectively is essential to the health of the extensive catchment area.
A free-flowing channel is also critical for boats travelling between Port Stephens and Tea Gardens.
The river entrance was dredged last year as part of a five year dredging program.
However, the rapid build-up of sediment has led to calls to use nearby earthmoving equipment to clear the channel.
"It surely would provide (Mid Coast) Council extra time before the next dredging campaign and also replenish the stockpile which has taken a bit of a hammering over the past week," Mr Grainger said.
There is also a push to assist nature to rebuild Myall Point, a sand structure that once jutted into Port Stephens.
A little-known fact about the estuary is that its three lake systems entered the ocean at different points up to about 1000 years ago.
Over time the three entrances were blocked through sand movement and the narrow stream which exists today was formed.
The single flushing point has led to the creation of a river 'plug' at Mungo Brush, which prevents the town from flooding.
"The plug diverts the flood waters back into the lake system so we don't get flooded, however, it also depends on the eastern entrance being open so the floodwater from the Karuah River doesn't come back into here," Mr Grainger said.
The two kilometre pipeline, which was commissioned last April, was designed to pump sand from a stockpile at Winda Woppa to 10 points along Jimmys Beach.
The project, jointly funded by state and local government, was undertaken after 30 years of research into the best way to deal with erosion at Jimmys Beach.
While opinions within the scientific and general community vary, the council took the position that ongoing replenishment was the best way forward.
