B-1
APPENDIX B: REVIEW OF THE SMITHS LAKE OPENING PROCEDURE
WITH RESPECT TO THE MARINE PARKS ACT
The following document outlines the risk assessment required by the Marine Parks Act 1997 for
the activity of artificial opening of Smiths Lake.
B.1 Introduction
The opening of the entrance to Smiths Lake is an important factor influencing the flooding around
the Lake. The entrance has been artificially opened since 1932, with Council coordinating the
activity since 1960 (WMA 2009). The trigger Lake water level, to initiate opening was initially set at
a 1.7m AHD, and since 2002, the level has been raised to 2.1m AHD. From 1990 additional
entrance management has included the specification of the entrance breakout location, to occur
approximately 150m north of the southern dune (WMA 2009).
B.2 Current Operating Procedure
The current operating procedure for the artificial opening of Smiths Lake is described below:
1. The Committee resolves to open the Lake (see Annexure “A” for Committee members)
2. The Committee notifies the following that the Lake is to be opened and the time of the
opening:

NSW Maritime Authority – Bret Ryan 6554 6004

State Emergency Service – Larry Thompson – 6554 0716

State Fisheries – Martin Angle – 6554 6078 or 0428 546 078

NSW Ambulance Service – 131233

Proprietor of Sandbar Caravan Park – 6554 4095

Proprietor of Frothy Coffee Boatshed – 6554 4202

NSW Police – 6555 1299 – the presence of at least one police representative is
considered essential for a nominated period after opening
3. A temporary fence barrier consisting of star pickets and barrier mesh to be erected a
minimum of 100 metres on the northern side of the proposed opening trench and extending
from the Lake edge to the beach high water mark. Sufficient materials for the construction of
the fences to be made available to the SES and Council Regulatory Staff before work are
commenced on the opening. Appropriate notices prohibiting persons from proceeding
beyond the safety fence to be provided for the use of the Council Regulatory officer before
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-2
the fence is constructed. The notices are to be left in place until sea level is established in the
Lake, normally 2 tidal cycles after Lake opening.
4.
A line of emergency buoys a minimum of 500 metres west of the proposed opening and at
appropriate intervals, to be put in place by NSW Maritime before the opening is commenced.
The location considered most suitable is a line from Bull Island north-east to the point
immediately west of Sandbar Caravan Park. A boat to be made available by Council or NSW
Maritime to enable the maintenance of a continual patrol of the buoy line until sea level is
reached.
5.
Ensure Lake is opened at opening position: GPS point 0454742, 6415678, located 160
metres north of south dune – Lake level approximately 2.1m AHD
6.
Ensure the Lake is opened on a falling tide
7.
Surveillance to be provided until the SES/Council agrees that it is safe.
B.2.1 Safety Precautions
The following safety precautions are conducted as follows:

Council regulatory staffs are present at each opening event from the time digging commences
until knock off time approx. 4pm. Staffs are responsible for installing a temporary boundary
fence consisting stakes and tape to encourage people to avoid the area. Regulatory staffs are
only available to assist if something goes wrong; they are unable to enforce penalties to
members of the public who ignore the barrier;

The SES is contacted and usually attends;

In the past the Pacific Palms surf life saving club has been notified of the opening and on
some years a life guard has been provided; and

The NSW Maritime Authority is contacted and buoys installed to notify boaters of the danger.
B.2.3 Issues
The following issues have been identified:

Council regulatory staffs are unavailable after approx. 4pm.

Regulatory staffs are unable to enforce penalties to members of the public who ignore the
barrier

The SES has stated that the opening event is not within SES jurisdiction and therefore it is not
appropriate for a volunteer to attend.

Surf Life Saving Club personnel are not always available due to the volunteer nature of the
club.

Staff not familiar with the opening procedure may follow the procedure incorrectly.
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-3
B.2.4 Risk Mitigation
The mitigation of risks is important to ensure the safety of the operators and the community. In the
following table (Table B-1) the risks associated with the activity of artificial opening of the Lake,
have been identified and following each risk are a control / solution.
Table B-1
Task
Hazard
Risk matrix for the artificial opening of Smiths Lake
Risk
Control (Solution)

Install appropriate signage notifying of the possibility of Lake Opening
following storm events at Lake Boat Launching points (see Figure B-1)
Water velocities

created pose a threat
to boats and
Have council and/or maritime patrol the Lake in a boat or on jet skis to
ensure the safety of boaters or swimmers.

swimmers
Contact one of the surf clubs to ensure lifeguard is in attendance should
a rescue be necessary.

Contact the SES to notify should a rescue be necessary and to help with
restricting access to the area.

Install adequate signage near the opening warning of the associated
dangers (see Figure B-1)
Bank collapsing on
Community

edge of opening
Safety
onlookers (see Figure B-1)

Close 4WD access points to Sandbar Beach (see Figure B-1)

Notify Sandbar Caravan Park owner and close access tracks to beach

Use of the media – radio and television broadcasting to notify residents
Public unaware of
Opening
risks
of
Cordon off area with mesh fencing to create a safe viewing distance for
of opening and associated risks.

Mail out brochure to all residents prior to any event to warn that the
event may happen and the associated risks when it occurs.
Smiths
Lake
Public ignoring safety

warnings
Volunteer staff
unavailable to help

Contact the local police as well as maritime to ensure appropriate action
can be taken if people ignore the warnings.

Ensure staffs on site have mobiles with reception coverage to notify
additional emergency services if required.

Ensure staff on site are proficient in first aid and carry a first aid bag

Lake to be opened on outgoing tide to reduce risk of tidal influences on
Incoming tide and
large waves pose risk
to heavy equipment
machinery
and operators
Contractor

Safety

Rain associated

Ensure that no onlookers are in the vicinity of heavy equipment
creates poor visibility

Cordon off access with wire fencing and star pickets (see Figure B-1)

Ensure appropriate clothing and footwear is worn to accommodate the
Protection against the
weather
climatic conditions e.g. typically heavy rains, wind.

Ensure adequate sun protection is undertaken (if required)
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-4
Figure B-1
Outline of entrance opening procedure locations
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-5
B.3 Incorporating Climate Change
The key aspects of climate change that are likely to impact upon the entrance opening procedure
are:

Sea level rise, and associated sediment transport processes (see section );

Increase in drought frequency and evaporation;

Decrease in annual rainfall but increase in extreme rainfall events; and

Small increase in wave climate
B.3.1 Shoreline recession
Shoreline recession due to sea level rise is likely to occur to the beach fronting Smiths Lake (see
section 5.7). Beach rotation, associated with climate change, however, is not likely to significantly
impact upon the entrance opening process, due to the location of the entrance in the middle of the
beach compartment.
B.3.2 Reduction in breakout frequency
The predicted reduction in total rainfall, combined with an increase in evaporation, is likely to result
in a reduction in frequency of entrance breakouts (as it would take longer for the ICOLL to fill to
the entrance berm height) (Haines 2006). The net upward shift in the Lake water levels combined
with generally flat topography of fringing lands means that the Lake may store a larger volume of
water before breaching of the entrance (Haines 2006). This would decrease the water level
response of the lagoon to catchment runoff inflows and reduce the frequency of entrance
breakouts (Haines 2006).
B.3.3 Transportation of marine sediment into the Lake
With increased sea levels and the landward migration of the beach, the entrance channel will
become shorter and deeper (Haines 2006). As a consequence, the frictional resistance in the
channel will be reduced and this will allow transportation of marine sediment further into the Lake
(Haines 2006). The increased water depth would also increase the flow conveyance area of the
channel, which would potentially reduce flow velocities and may result in a vertical accretion of the
marine delta rather than an immediate landward progradation.
B.4 Recommendations
The following are recommendations to allow for adaptive management to incorporate ongoing
acquired knowledge and climate change into the entrance opening procedure:

Determine the most appropriate location for entrance opening to optimise breakout
effectiveness: This allows for a variation (within an acceptable range) in the GPS location for
the entrance opening to enable adaptive management accounting for antecedent conditions,
as well as longer term climate change where the beach berm is likely to migrate landward and
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-6
upward. The current monitoring of entrance characteristics, during artificial openings, is likely
to identify if a change in GPS location is warranted i.e. when the entrance channel is not
operating effectively, with shorter openings or reduced water outflow.
For example, following the Estuary Management Committee Meeting in August 2011, it was
agreed that the next opening should be closer to the southern dune (no closer than 75 m but
within 100m). The last opening, in May 2011, was followed by a large easterly swell which
pushed a substantial quantity of sand into the entrance channel and as a result it will be
necessary to move the GPS opening location from the current position in order to achieve a
suitable opening. As such the next artificial entrance opening could occur as far south as
0454724, 6415591

Periodically review the trigger water level for entrance opening: As the beach berm
increases in height and migrates landward, the current trigger water level will allow for less
water volume within the Lake. Under the current regime this will promote more frequent
intervention from Council to mitigate against flooding of low lying infrastructure.

Investigate mitigation options for low lying infrastructure: As sea level rises, and the
capacity of the Lake to contain flood waters is reduced, low lying infrastructure will become
increasingly under threat from flooding. To reduce Council‟s intervention and liability, it is
recommended that low lying infrastructure is incorporated into a long term program to retain
(and protect or modify), retreat or remove the infrastructure.

Community Awareness: Community education programs will aid in community acceptance
of changes that will be required to manage the entrance into the future.
B.5 Marine Parks Act Assessment
st
The Port Stephens–Great Lakes Marine Park (PSGLMP) was declared on the 1 December 2005
under the Marine Parks Act 1997. The marine park covers an area of approximately 98,000
hectares and includes the estuarine waters of Smiths Lake and all of its tributaries and creeks to
the limit of tidal influence (MPA 2007).
The ecological characteristics of Smiths Lake are largely controlled by entrance management
actions, predominantly in terms of changes to water levels as well as changes to water level
variability and flushing, which in turn affect water quality. As such, there is a need to review the
current Opening Strategy in terms of whether the existing ecological values are maintained by
entrance management actions.
B.5.1 Significance of inclusion within a Marine Park
In particular, as the Port Stephens - Great Lakes Marine Park was declared after the development
of the Smiths Lake Opening Strategy, there is a need to assess whether the current opening level
and procedure is consistent with the objectives and Principal Assessment Criteria of the Marine
Parks Act 1997 and the accompanying Regulations. Note that these objectives and assessment
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-7
criteria have been described in detail in Section 10.2.8 and the entrance of Smiths Lake lies within
the Habitat Protection Zone of the marine park.
Based on the background information review conducted as part of EMP review, the ecological
values of Smiths Lake that are seen as important with respect to inclusion of the Lake in the
marine park are summarised as follows:
o
Extensive seagrass, saltmarsh and wetland areas;
o
Presence of threatened fauna, flora and vegetation communities;
o
Diverse and abundant fish populations; and
o
Important fish breeding and nursery grounds.
Therefore, in order to be consistent with the Act, the opening strategy must aim to protect these
underlying ecological values.
The current Opening Strategy was developed so as to negate any potentially adverse impacts on
ecological characteristics, such that it aims to maintain all of the above-mentioned values and is
consequently in accordance with the objectives of the Act. Furthermore, as the current Opening
Strategy aims to simulate the natural hydrological regime, the inhabitant ecological communities
are expected to display adaptive responses to entrance management.
B.5.2 Risk Analysis
A preliminary qualitative risk analysis was conducted in order to investigate the impacts of
entrance management on the ecological values that underlie inclusion of Smiths Lake in the
marine park. Firstly, specific risks were identified in the context of the Marine Parks Regulation
assessment criteria. The risks that were developed are as follows:
o
Reduction in extent or loss of seagrass beds;
o
Reduction in extent or loss of the saltmarsh EEC;
o
Reduction in extent or loss of fringing wetlands including the EEC;
o
Loss of Threatened flora species;
o
Loss of Threatened fauna species;
o
Reduction in abundance or loss of fish populations; and
o
Reduction in extent or loss of fish breeding grounds.
Following identification of the risks, major controls on the ecological values were described in
order to evaluate linkages between the existence of the ecological values and management of
entrance opening. These are presented in Table B-2.
Table B-2
Value
Key controls that maintain the ecological values
Key Controls
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-8
Seagrass




Saltmarsh
 Period inundation
 Brackish to saline water
Fringing wetlands
 Occasional inundation
 Freshwater
Threatened flora
 Coastal sand dune habitat
Threatened fauna
Threatened fauna are maintained by the persistence of fringing
wetland habitat; therefore, in the context of this assessment, key
controls for Threatened fauna are consistent with the above key
controls for fringing wetlands
Fish abundance
Fish breeding and populations are maintained by the persistence of
seagrass habitat; therefore, in the context of this assessment, key
controls for these two values are consistent with the above key
controls for seagrass
Fish breeding
B.5.2.1
Permanent inundation
Saline water
High level of water clarity
Good water quality (i.e. no excess of nutrients)
Incorporating Climate Change
One of the most significant impacts from climate change, upon the lake ecology, is likely to be
from projected sea level rise. The extent of the impacts within the Lake will be governed largely
by the status of the entrance, and therefore are tied closely to the entrance opening policy and
procedure.
Three scenarios were chosen to represent current and possible future conditions, dependent on
entrance management and sea level rise. Each risk was then analysed under the following
scenarios:

Current Opening Strategy;

Possible change in Opening Strategy in which water level is significantly lowered; and

Possible change in Opening Strategy in which water level is significantly raised.
The analysis process involved assigning each risk a „likelihood‟ and a „consequence‟ in order to
categorise the risk as low, medium or high (refer Table B-3). The outcomes of the risk analysis
are provided in Table B-4, followed by a discussion on interpretation of the risk analysis.
Almost Certain
Likely
Likeliho
od
Table B-3
Matrix for risk analysis
Medium
Medium
High
High
High
Low
Medium
Medium
High
High
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-9
Possible
Low
Low
Medium
Medium
High
Unlikely
Low
Low
Low
Medium
Medium
Rare
Low
Low
Low
Low
Medium
Negligible
Minor
Moderate
Major
Catastrophic
Consequence
Table B-4
Risk analysis for current, raised and lowered water levels
Risk
B.5.2.2
Current
Raised
Lowered
Reduction in extent or loss of seagrass
Low
Medium
Low
Reduction in extent or loss of saltmarsh EEC
Low
Medium
Low
Reduction in extent or loss of fringing wetlands including EEC
Low
Medium
Low
Loss of threatened flora species
Medium
Medium
Medium
Loss of threatened fauna species
Medium
Medium
Medium
Reduction in abundance or loss of fish populations
Low
Medium
Low
Reduction in extent or loss of fish breeding grounds
Low
Medium
Low
Interpretation of Risk Assessment
As the ecological communities within and directly adjacent to Smiths Lake are characteristically
suited to the changing environment of an intermittently opening and closing Lake, entrance
management actions are not likely to have profound adverse impacts on the ecological values.
Rather, an ecological balance is expected to be maintained over time although short-term adverse
impacts may be observed, resulting in a „low‟ overall risk. Specifically, fringing saltmarsh and
wetland communities are expected to gradually migrate over time in alignment with the water level
(e.g. there may be an initial loss of saltmarsh, followed by recruitment of saltmarsh into new
areas). Similarly, the distribution and species composition of seagrass communities are expected
to change over time in response to the opening procedure. In other words, while the specific
distribution and composition of ecological values may change, the overall extent of ecological
values is expected to remain within the bounds of natural variability.
In the context of migration of vegetation communities, it is noted that no barriers to the
encroachment of vegetation have been observed in this assessment. Specifically, no roads,
developments or other infrastructure are located directly adjacent to the relevant vegetation
communities, such that there is the opportunity for successive movement of vegetation
communities.
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx
B-10
The loss of threatened flora species has been assigned a „medium‟ risk rating under all scenarios
due to the proximity of the species to the location at which entrance management works will be
undertaken. However, this risk can be negated by ensuring that activities do not interfere with any
Sand Spurge individuals. Similarly, the loss of threatened fauna species largely refers to direct
habitat disturbance associated with entrance management works (e.g. disruption of avifauna
breeding on the sand barrier).
This risk can also be negated by ensuring that potentially
interfering activities are not undertaken at a time at which protected fauna species are breeding.
With respect to the remainder of the „medium‟ risks, these are all associated with the scenario
under which the water levels would be significantly raised. A more closed entrance would result in
accumulation of nutrients and reduction in salinity, which would not be favourable for seagrass or
saltmarsh communities. In turn, fish breeding grounds and fish populations would be negatively
impacted by reductions in seagrass.
Under this scenario, fringing wetlands may also suffer
through increased inundation. However, it is to be noted that these are generalised assumptions
that are based on a scenario under which water levels are raised close to the maximum, and that
relatively minor increases in the water level are not expected to result in significant impacts.
B.5 Conclusion
In conclusion, although consent will be required in accordance with the Marine Parks Act (and
other relevant Acts), it can be demonstrated that the current Opening Strategy is unlikely to have
any adverse impacts on the ecological values of the system.
K:\N1797_SmithsLake_EMP_Review\Docs\R.N1797.002.00.AppendixB.docx