Devastating bushfires and the effects of recent flooding is threatening an industry dependent on nature for its survival.
Chair of the NSW Farmers' Oyster Committee Caroline Henry, who runs Wonboyn Oysters inside Wonboyn Lake, said extra nutrients brought by bushfire debris into the water systems had already created algal bloom issues.
"There's a hell of a lot of ash, so there's a lot still to come," she said.
Shellfish harvest areas from Bermagui to the Victorian border were closed on Tuesday due to concerns over the recent heavy rainfall.
Ms Henry said, added to ongoing cashflow issues, the full environmental effect of the post-fire period may not be felt by the industry for months.
In January, the NSW Department of Industry held discussions with members of the oyster industry on the need to prepare for potential impacts of rainfall runoff from the fire grounds over the next 18 months.
At the meeting Ms Henry requested immediate assistance through the state response team, and members shared their concerns over oyster producing estuaries either closed to the sea or under threat of closure due to the drought conditions. Wonboyn Lake, while open the majority of the time, did close last year.
Ms Henry said Bega Valley Shire Council had placed a dry notch last week at the lake to reduce the impacts of low level flooding after 90 per cent of the catchment was hit by fires, and the lake had semi-opened over the weekend.
We're staying positive.Chair of the NSW Farmers' Oyster Committee Caroline Henry
Council said on Wednesday a review of environmental effects has been completed by consultants Elgin, with "additional studies being undertaken by MHL to further investigate the hydrodynamics of the estuary and flushing rates".
"The NSW Department of Planning, Industry and Environment have installed a series of loggers in the estuary and continue to undertake water sampling to understand the influence on the increased tidal exchange," council said.
"Council is awaiting further results both from studies and ongoing sampling. This information will also be beneficial to other estuaries as it improves our understanding of fire related impacts on estuaries on a broader scale."
After the January meeting the state government agreed to increase water monitoring and also to approach the Tasmanian oyster industry to learn from their bushfire experiences.
Members also requested a discussion with the relevant agencies around the potential impacts from fire control and containment actions within catchments.
"We're staying positive," Ms Henry said.
"I love the industry and everyone who works in it."
Council said the sediment and ash ending up in the waterways can increase turbidity, alter the pH levels and reduce dissolved oxygen, which can effect a whole range of other species in the lake.
"The effects of a significant rainfall event post-bushfire may result in detrimental impacts to seagrass communities due to sedimentation, a higher risk of fish kill due to reduced levels of dissolved oxygen, and elevated nutrient concentrations with the potential to stimulate algal growth," council said.
Works have subsequently been done on the entrance to reduce the berm at the mouth in order improve tidal exchange in the lake.