The East Gippsland Catchment Management Authority (CMA) have been monitoring conditions at Lake Tyers estuary with Parks Victoria, Gippsland Ports and the Victorian Fisheries Authority (VFA) pending a potential artificial opening of the estuary.
Lake Tyers estuary has been at a high level of water inundation for some months now and with not enough water flowing through the catchment the estuary has remained closed.
At this stage, it is unlikely the East Gippsland CMA will authorise an artificial estuary opening with the current conditions due to low oxygen levels in the lakes and the potential impacts to black bream breeding cycles.
“We understand the varied impacts of estuaries remaining closed for long periods of time. It is a delicate balance of social, cultural, economic, and environmental values to consider and many aspects to assess when considering artificially opening an estuary” said Bec Hemming, CEO of the East Gippsland CMA.
The key risk is that, immediately after an artificial opening the oxygenated surface water layer drains out to sea. This process, termed de-oxygenation, can leave behind water that is low in oxygen in the deeper areas of the estuary or that has drained from the surrounding land. A lack of oxygen is the primary cause of fish deaths. We have been monitoring Lake Tyers estuary and oxygen levels are very low, particularly at the bottom of the lake.
We have seen this in the past with a substantial fish death event some years ago when the Betka estuary was opened illegally causing the oxygen levels to become too low for the fish to survive.
“We understand the frustrations from community members and other organisations whose assets are inundated with water, considering all aspects of artificially opening the Lake Tyers estuary we feel the environmental risk is just too great at this point in time.”
“It is finding that balance that ensures a successful outcome for all. Recent community discussions have highlighted the impacts of sustained high-water levels, improved understanding and created more opportunities to share information.”
The East Gippsland CMA and Parks Victoria have also determined that the impacts to vegetation in areas inundated by high water levels has not been extreme nor out of the normal range from other conditions such as drought, vehicle damage or general aging.
“We will continue to monitor conditions and assess the opportunity for an artificial opening, particularly if a substantial rainfall event is forecast.” Added Bec
