Balancing competing objectives in coastal entrance management

The south-east coastline of Australia contains an internationally significant cluster of coastal waterways which intermittently open and close to the ocean. These waterways are valued for a variety of recreational, ecological and aesthetic reasons. In many locations, residential development and its associated infrastructure has occurred without full appreciation of the high water levels that might be experienced within these lagoons when they are closed. Continuing sea level rise will also act to raise water levels into the future. Key conflicts arise between existing residential development, which often requires that a closed waterway entrance be artificially breached and a desire, from some in the community, for less intervention based on the assumption that this would result in more 'natural' outcomes that are intrinsically beneficial for ecological processes. This paper describes approaches taken to try and balance these competing concerns within the Central Coast Local Government Area, to the north of Sydney. A project which considered eight separate coastal waterways with varying physical characteristics, values and pressures was recently completed. Historically, the entrances to those waterways were managed almost exclusively to mitigate the damage caused by flooding of low lying, fringing development. The repeated artificial breaching of the lagoons has, in some instances, resulted in changes to water quality and ecological functioning of those systems. Due to present social, legal and funding constraints, the options that Central Coast Council has available for altering the existing management regime are limited. The mitigation of flood risk is still an overriding concern for management decisions, however, small changes were considered sensible to allow some positive ecological outcomes and these provide some indication of how coastal entrance management may need to evolve in the future.