Wallaga Lake entrance opening in danger of closing again

The opening of Wallaga Lake late last month has not resulted in the clear water and tidal flow everyone had hoped for.

The new opening entrance may even close again soon, although heavy rain forecast this week could help.Things had improved a little in recent days with a bigger opening being scoured out and more tidal flow, thanks possibly to recent rains and the flow of water out through the channel.

Bega Valley Shire Council has admitted the lake was opened prematurely before the trigger point was reached to allow for work on the causeway road.

Ironically, the lack of a proper opening has allowed the water to escape but now the lake level has fallen very low, exposing sand and mud flats.

Lindy Quin from nearby Couria Creek has taken photos of the low water levels in the lake and posted to social media.

“I deliberately went to take photos at high tide and wasn't expecting the lake to be this low,” she wrote. “The opening is shallow and has a sandbar just off it which is causing the waves to break and not push in.

“On both the east and west sides of the causeway remain as mud flats even at high tide.”

Bega Valley Shire Council coastal management officer Kyran Crane said the lake was opened below the opening trigger to alleviate the damage to the road and hence the public safety risk.

“The opening trigger is some 15cm higher than the level it was opened on this occasion.” he said.

“While 15cm doesn’t sound like a lot, over the entire lake it equates to a significant amount of water which in turn scours out the sand at the entrance and leads to a more successful and longer lasting entrance opening.

“It is evident from the past opening that there wasn’t enough ‘head differential’ between the lake and ocean and it is a good reminder of why we need to let these ICOLLs (Intermittently Closed and Open Lakes and Lagoons) reach as high water levels as possible before opening. Unfortunately in this case the road was a priority for opening.

“We have had some good rainfall over the weekend and some more forecast this week so hopefully it will assist in scouring more sand out of the entrance and lead to a better entrance channel.”

Local residents including Sean Burke had commented that perhaps the opening would have been better if it had been dug more to the north, which may have allowed a greater and faster flow in the initial breaching stage. 

Mr Burke also commented on the Narooma News Facebook page about the state of the lakes.

“One problem of the last 100 years or so is the amount of sand that has been released from rivers up and down the coast due to land clearing and logging. This sand moves along the coast and clogs up the mouths of our estuaries,” he wrote.

“To leave it to nature to open the mouth would certainly be good for the riparian zones surrounding the lake and adjacent wetlands but it would mean that lots of structures put in since European settlement down here, including the road, would be underwater for quite a long time.

"That's why the Entrance Management Strategy set the road as the trigger point for artificial opening and recommended that all low-lying assets be raised over time so that the trigger point can also be raised for a better scour.”


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