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Deep Creek ICOLL

Nambucca Shire Council

Development of an estuary management plan and flood risk assessment.


Deep Creek is an ICOLL on the NSW north coast which is largely open. WMAwater conducted a flood study and climate change assessment for Council. Little historical flood information is available for the catchment. The catchment recently experienced a large flood event. No flood study had previously been undertaken for the catchment. Council wished to undertake a flood study and develop an estuary management plan. The estuary berm was causing nuisance flooding of properties and as a result the berm was being illegally opened.


We used knowledge of the nearby catchments calibrated to the same event to inform the study. As part of the study a range of closed entrance berm heights were assessed for their impact on flooding. An assessment of climate change (water level and rainfall) and increased berm heights was undertaken. The residence times of the ICOLL were also assessed. Based on model results an entrance opening strategy was recommended which aimed to increase the natural aspects of the ICOLL and reduce human intervention.

  • An understanding of flood risk on the catchment
  • Improved flood planning levels for the catchment
  • Estuary management plan that balances a natural system and reduces human intervention.