Walkers and surfers at North Head Brunswick Nature Reserve will find a very sad scene of environmental destruction.
The beach is being dug up and dredge slurry is being being piped into holding ponds by the dredge operators in the Brunswick River.
This is a beautiful and pristine stretch of beach adjacent to a nature reserve and adjacent to a natural reef, it should never be turned into a spoil tip.
I suspect that this dredging operation is purely politically motivated tick, a pre-election promise for waterway dredging made by the state government despite all evidence that the taxpayer money is being thrown away when used to fund this type of dredging operation.
No in-depth assessment of need for dredging has been conducted at specific rivers. Studies show that the silting up of the river is a natural process that will occur faster following dredging, and replace what has been removed.
Within a year or two you can expect to have the same water depths as prior to dredging.
There is no fishing fleet on the Brunswick River, my understanding (derived from conversations with trawler owners when they still operated out of the river) is that this is mainly because of an only intermittently passable bar for large boats that can travel the large distances required to find fish.
Notably the bar will not be dredged in this operation, presumably because it is known to be a fruitless exercise. This is a small river with a usually small flow that is not suitable for large fishing fleets. There is no real reason to dredge the river.
The lower Brunswick estuary is a benthic system with seagrass beds and micro algae growing on the surface of the sediments and sediment infauna including worms and small bivalves providing important food sources to fish.
This ecology and their food webs will be destroyed by dredging.
This project has been rushed through for political reasons, the council has asked for a number of questions relating to the necessity and environmental impacts to be answered prior to dredging commencing, it is extremely unpopular with the locals, but the state government has bulldozed it through.
The REF finds that:
‘Positive impacts include maintenance of navigation channels and the boat harbour to allow for commercial and recreational boating and fishing which are highly valued pursuits in the locality.
This is incorrect as the channel will infill rapidly and as the size of boats using the river is limited by the depth of the bar. The area to be dredged is navigable by most boats at low and high tide currently, and at high tide for some boats that cannot cross the bar at low tide in any case.
‘Short-term adverse impacts include noise, vibration, reduction in visual amenity, restricted access to beach areas (during stockpiling, dewatering and beach nourishment activities), and minor changes to boat passage while dredging is underway.
‘At the southern end of New Brighton Beach only a small proportion of the beach will be occupied by the works at any one time, however heavy machinery will detract from beach amenity and recreational use during works.
‘While there are negative impacts expected during the works, the impacts will be short-term and are considered minor. In this context, and considering implementation of environmental measures as discussed in Section B, it is considered that the impact of the works is low.’
This is a subjective assessment of minor impact.
Notably the REF does not take into account the impact of digging the beach up and exposing deeper fine sediment that are likely to become acidic and during rainfall events are likely to form a plume in the near shore, endangering the survival of reef and beach flora and fauna.
This possibility far outweighs any positive outcome attributed to beach nourishment, which given the dynamic nature of the sand budget, is not a significant positive outcome.
The REF water quality protection measures include:
• Dredge operators should carefully monitor the fines
content from dredge area AB to ensure that the dredged
material that is pumped to the beach nourishment area is
consistent with beach sands at that location.
• Within dredging site C, sediment beyond approximately
2.4 m below Brunswick River Flood Mitigation Datum
(BRFMD) is not suitable for beach nourishment due to
relatively high silt/clay content. As the target channel
depth is -2.5 m at this location, the volume of this muddy
material may be insignificant; however the dredging
contractor should carefully monitor the fines content to
ensure that dredged material is consistent with the beach
sands on New Brighton Beach. Should unsuitable material
be encountered it will be redirected in order to be
dewatered and transported along with the boat harbour
sediments.
These required measures, while acknowledging the introducing fine sediment from the estuary, does represent a serious risk to the beach environment, it does not take into account the introduction of fine sediment from below the sand dune in the digging process to create slurry holding ponds.
The photograph attached clearly indicate fine sediment from below the dune has now been deposited on top of the beach, which must be in violation of the REF requirements.
This situation alone should trigger a halt to works on the beach.
Given that there is no need or positive result from dredging, there is no excuse for causing obvious harm by digging up the dune or risking unknown further environmental harm.
Dr Jennita Gay, South Golden Beach
