13.2 The Wallis Lake Estuary Management Committee - Great Lakes ...

Wallis Lake Estuary Management Plan
Management Objective Consider managing all maintenance dredging activities in Wallis Lake by developing and implementing a Wallis Lake maintenance
dredging strategy
S.3
Management Area A, B & C
Action
No
S.3.1
S.3.2
S.3.3
S.3.4
Action
Continue investigations into the development and operation of a permanent sand
deposit area on Tern Island subject to development approval
Rehabilitate Godwin and Cockatoo Islands once a permanent sand deposition
area is operational
Prepare a Wallis Lake maintenance dredging strategy by:
• adapting the Wallis Lake oyster lease maintenance dredging protocol to
form Chapter 1
• developing protocols for the maintenance of major navigation channels
ensuring safe depths for water vessel passage to form Chapter 2, and
• developing protocols for the removal of sediment build-up at major
stormwater drains to form Chapter 3
Conduct periodic hydro-surveys to monitor the rate of infilling of dredged areas
from action S.1.2
Indicative
Cost
Priority Responsibilities Progress
$1 million High (B4) GLC, DIPNR, EIS completed (Webb,
Lands
McKeown and Associates
2004)
$350,000 High (B3) GLC, DIPNR,
Lands
$40,000 Medium (B5) GLC, DIPNR,
Lands
$20,000 Medium (B5) DIPNR
Comments
The Tern Island project is a problem solving and not a profit making exercise. Any surplus funds arising from the operation of the project will be reinvested into the environmental
maintenance of the estuary.
Maintenance dredging of oyster leases undertaken in accordance with the Wallis Lake oyster lease maintenance dredging protocol requires consent from one authority (GLC) due
to a recent amendment to the EP&A Regulation 2000 under the EP&A Act 1979.
S.3.2 will involve removing excess sand that has been dredged up onto Cockatoo and Godwin Islands and rehabilitating the wetlands on these islands.
Protocols for the maintenance of navigation channels and stormwater drains should include criteria that must be met to be eligible for the strategy. These criteria must consider
sediment stability, cost/benefit, habitat value, navigation and public safety issues. For navigation channels, these criteria may determine the number of times within 6 months a set
minimum depth is breached at high tide. A 6-month time frame is a reasonable time frame to wait for the occurrence of a flood event to naturally scour the channel. The depth the
channel is to be dredged should be determined after consultation with the various user groups to ensure equitable access.
All dredging undertaken in the Wallis Lake maintenance dredging strategy should ensure that dredging operations do not increase the risk to seagrass, mangrove, saltmarsh or
other areas of high conservation value or adversely impact upon water quality and should consider any possible adverse impacts upon recreational and commercial fishing
activities.
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