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Bega Valley Shire CouncilBega Valley Shire Council

Wonboyn Lake Entrance Management Policy

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Background

Following the closure of the Wonboyn Lake entrance in late 2019, and negotiations around appropriate entrance opening triggers, the Wonboyn oyster industry, Council and NSW Fisheries identified that finalisation of a sustainable entrance management policy was required to support commercial, recreational and ecological activity in and around Wonboyn Lake. The entrance to Wonboyn Lake has historically been open for the majority of time, and much of the foreshore and in-lake infrastructure is designed for relatively low water levels.  This regime has supported a commercially viable oyster industry.  Over the last 10 years or so, an increasing trend of heavy entrance shoaling, and closure events have occurred.  These intermittently closing and opening conditions typically do not support commercial oyster production.

In NSW, coastal management legislation supports minimal interference with intermittently closing and opening lakes and lagoons (ICOLLs), preferring that natural processes be allowed to operate to the greatest extent possible.  The mechanical opening of lake and river entrances typically takes place to reduce the impacts of flooding on public and private infrastructure with opening trigger heights for each estuary determined by heights of key local infrastructure.   The effectiveness of entrance opening is greater at higher water levels, as there is increased likelihood of a more prolonged opening and scouring of the entrance area sand shoals, resulting in enhanced tidal exchange and an increased chance that the entrance will remain open for an extended period.

Historically, Wonboyn Lake entrance has been open, with the only known closures occurring in 2004, 2009 and 2019.  Extended periods of closure are problematic for the oyster industry due to impacts on temperature and salinity within the lake and inundation of foreshore infrastructure including jetties and leases.

Due the traditionally open state of the Wonboyn entrance, foreshore recreational and commercial infrastructure has been built at relatively low elevation in order to be functional in a tidal environment. Generally, the when the lake is open water levels fluctuate between 0.1 0.4 metres above the Australian height datum (m AHD).

Elevated water levels for extended periods of time, such as occurred in late 2019 / early 2020, pose a risk to health of oyster stock, affect oysters farming operations, create on-water navigational hazards and cause damage to oyster lease infrastructure. There is also a range of private infrastructure around the edge of the lake, including boat sheds and jetties which sit as low as 0.34m AHD, with a majority below 1m AHD.

Currently, with no policy in place, there is a great deal of uncertainty for stakeholders and the broader community regarding the conditions under which Wonboyn will be mechanically opened. The series of approvals and permits required from NSW Government agencies to undertake entrance works can further delay openings. This policy will provide the oyster farmers and Wonboyn community with certainty around opening procedures and a benchmark for a future trigger height to plan for. It will also increase Council’s responsiveness, improve consistency with management of other ICOLLs in Bega Valley Shire and affords Council certainty regarding entrance management options.

Who's listening

  • Rachel Duczynski
    Coastal Management Officer
    Bega Valley Shire Council
    Phone: 02 6499 2179

Project timeline

 

Have Your Say

A Community drop-in session will be held on Saturday, 14 November 2020 from 8:00am to 12:00pm (noon) at the Wonboyn Fire Shed. Please drop in anytime between 8am and noon to have a chat, give feedback or ask questions.

Due to Covid-19 restrictions the number of people within the fire shed at any one time will be limited.

A zoom information session will be held online on Thursday, 5 November 2020 from 6:00pm to 7:30pm.
This will be an informational session which will cover ICOLL facts, background of Wonboyn Lake, current issues and the Policy which has been developed with some time for questions at the end. Please check back here prior to the meeting for zoom access details.

Feedback and/or questions can be shared via the comments section at the bottom of this page or via email council@begavalley.nsw.gov.au.

Please submit your feedback by midnight Thursday, 19 November 2020

 

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