WATER authority, GHCMA, is alleging the mouth of the Surry River at Narrawong was illegally opened by hand on Wednesday evening ahead of heavy rains.
“The illegal opening of the river mouth was confirmed through evidence of a small (shovel-width) channel being dug in the sand bar between the sea and the river,” Glenelg Hopkins Catchment Management Authority (GHCMA) chief executive Adam Bester said.
“The timing of the opening (before 8.30pm) has been supported by data from monitoring stations along the river which indicate a rapid drop of river levels, not in line with a rainfall event.
“The opening also occurred on an outgoing tide, resulting in fish being stranded at the river mouth.”
Mr Bester made the accusations yesterday morning after water levels at the river dropped considerably overnight, with fish dying in the process.
The illegal opening allegation was quickly refuted by local landowner Owen Roberts, a vocal advocate for better management of the estuary’s regular flooding and release cycle.
“That’s almost laughable: it was so full it was starting to seep out late yesterday (Wednesday),” Mr Roberts said.
“If anyone was going to open it they would have done it a week or two ago.”
Mr Roberts said he had observed a water drop by 9pm, and estimated it had breached the sand bank at the river mouth between 7 and 8pm.
The river mouth opened just hours after photos of the high-water levels were taken by the Portland Observer, and GHCMA and Mr Roberts had agreed the water had peaked above records set at least 20 years ago.
Both parties had also expressed fears of fish kills if conditions were not right when the river mouth opened.
Mr Roberts and other locals on Wednesday said they were worried about damage being caused to the area, including local infrastructure, due to the inundation and if the water flowed out too rapidly when the river mouth did open.
By yesterday morning it was clear that many fish deaths had occurred.
Mr Roberts said the fish had been caught as the water flowed out rapidly, and some people had been observed collecting dead fish yesterday morning, perhaps to use as bait, and effectively “removing evidence,” about what had occurred.
GHCMA said their investigation into the fish deaths was continuing, and “but it was likely caused due to a lack of oxygen in the water.”
“Monitoring of dissolved oxygen on Wednesday, July 1, was measured at 0.4 mg/litre.
“Fish required those levels to be at least 4 mg/litre to warrant a safe opening.”
“Over autumn and early winter, when inflows are low, our estuaries are naturally stratified, with saline stagnant (low oxygen water) sitting at the bottom and fresher water from the river flows sitting in a layer on top. A poorly timed opening will result in most of the freshwater draining away leaving only poor quality (low oxygen) water in the estuary. This not only affects fish but all organisms in the estuary,” Mr Bester said.
“We were expecting a heavy downpour this week which would have potentially provided enough freshwater mixing with current flows to improve water conditions and allow a safe opening. Unfortunately, the river was opened illegally before this could happen.
“The last time we had a significant fish death event on the Surry River we lost over 30,000 fish: it took years for the river to recover from that incident,” he said.
Mr Roberts said on Wednesday he believed the water had not been so high since 1946, after three to four days of heavy rain when the river mouth was already open to the sea.
Caravan Park Rd, which was built up by Glenelg Shire Council after a similar 2006 flood, was waterlogged and also had water over it.
“That will erode the road,” he said.
Barriers built on his farmland to the west of the estuary had been breached, with water travelling into a neighbouring property on Tuesday night.
Water levels on the Narrawong Recreation Reserve were also unprecedented, he added, with a new “lake” formed from the river to across the road used to access the Narrawong Holiday Park and across to the reserve’s oval.
“Water is also coming up through the ground at the reserve,” Mr Roberts added.
“This will not be allowed to reoccur to this extent: there will be representations made to all government levels to review catchment management policies: they just have to change.”
Cape Nelson’s Bureau of Meteorology weather station data was not published online on Wednesday evening or yesterday morning, however 10mm of rain was recorded at Portland Airport between 6pm Wednesday and 4.30am yesterday.
Wind gusts peaked at 65km/h at 7.26pm and 7.39pm, and had consistently been above 40km/h since 7pm.
* In a statement to the Portland Observer, on Wednesday the GHCMA noted that the Surry River “is recognised internationally as an intermittently closed estuary, which means the mouth of the river closes naturally as freshwater flows from the catchment reduce and ocean conditions form a sandbar across the mouth of the river.
“It is an entirely natural process and helps to support a range of species including birds, fish, frogs and floodplain and wetland vegetation.
“It is typical at this time of year for the estuary to naturally close, predominately due to low instream-flows.
“It is important it does this, as the natural opening and closing of the estuary triggers fish spawning cycles, bird feeding, breeding and migrations, vegetation integrity and nutrient cycling.
“This is one of the main reasons why the estuary is so productive and attracts a number of anglers and tourists.”
GHCMA noted that it is illegal to open an estuary without a permit authorised by them.
A person or people found to have contributed to an unauthorised river mouth opening could be prosecuted under the Water Act (1989) and face fines or imprisonment.
* A Glenelg Shire Council spokesperson said on Wednesday that Glenelg Shire Councillors and chief executive Greg Burgoyne had been to the Narrawong Recreation Reserve on several occasions, and a select number of roads in the area that are managed by council had had warning signs erected.
“Council has been contacted by a number of residents on the rising water levels, and we too share their concerns,” the spokesperson said. “We are in frequent communication with the GHCMA to advocate on behalf of the community and help ensure appropriate and effective action is being taken, both now and for the sustainable future.”