Most local councils on the NSW coast have entrance management procedures in place where low lying infrastructure is present, and many include being able to artificially open the lake or lagoon to the ocean. This procedure is started when the body of water reaches a 'trigger level' or 'trigger condition', as set out in the relevant management plans.
Many factors affect the Council’s decision to artificial open the lakes. Generally, when performed during wet weather, opening can limit the scour and result in a weak breach and more sand ending up in the entrance channel. As a result, the flood tide delta may expand into the estuary, causing the entrance to close over more quickly (DPIE, 2020).
During dry weather, the local community often calls for the opening of the entrance in a bid to improve perceived poor water quality. This action has very little effect on flushing, does not encourage effective scour, brings more sand into the channel and closes over quickly.
In fact, frequent artificial openings at low trigger levels can cause the entrance compartment to become clogged with sand over time, decreasing the effectiveness of subsequent openings (DPIE, 2020). Coastal experts advise that to maintain a healthy lake, entrance management should be as close to natural as possible.
