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Change in Lake Macquarie is a process of continuous
evolution. It is natural, constant and in many cases
desirable. The challenge we face, is to manage the rate
of change, which has been accelerated by human activities,
to achieve our goal of a healthy and functioning ecosystem.
The environment will never return to 'how it used to
be', because of the natural evolution that is always
occurring. The Lake is constantly ageing and has a limited
life span. In fact, even without human intervention,
Lake Macquarie would eventually fill in through natural
processes. However, maintenance of a healthy ecosystem
is possible by reducing the quantity of nutrients and
sediments entering the Lake with stormwater.
The most obvious signs of this infilling occur around
the mouths of the larger creek systems. When the velocities
of the creek slow as the waters mix with the lake, sediments
drop out to form extensive delta areas. For example,
the area known as Five Islands at the mouth of Cockle
Creek, has filled in so rapidly it is barely possible
to distinguish the former five islands.
In geological terms Lake Macquarie is still quite young,
formed only 6,000 years ago. Many parts of low lying
suburbs such as Dora Creek, Blackalls Park, Speers Point
and Teralba, located nearby to creek systems were actually
part of the Lake only a few thousand years ago.
Prior to Europeans settling in Lake Macquarie, the
flow of sediments into the Lake was estimated to be
at a rate of approximately 6,600 tonnes per year. By
1983, the then State Pollution Control Commission estimated
that sediments were flowing into the Lake at a rate
of approximately 75,000 tonnes per year. With this type
of exponential increase in sediments and nutrients,
it is easy to see why Lake Macquarie became such a stressed
Since the early 1990's, we have learnt a lot about
the natural systems within our environment and the role
they play in maintaining balance and wellbeing within
We have also identified some of the many contributors
to increased sedimentation and nutrient enrichment and
through community awareness and behavioural change within
the catchment, we have had some success in addressing
In 1998 the Lake Macquarie Task Force established by
the NSW Premier estimated the flow of sedimentation
into the Lake to be approximately 57,000 tonnes per
year and some believe that it has since reduced even
further. It is a trend we need to continue.
Supporting natural filtration systems like wetlands
and vegetated areas (especially around creek banks and
in drainage lines) is important as they remove contaminants
from stormwater to reduce the stress on the lake.
The Project Management Committee has funded a number
of projects which re-introduce natural processes back
into the environment. These include the construction
of wetlands, sedimentation traps and vegetated drainage
swales. While these projects will never fully replicate
the natural processes, by mimicking them we can help
the environment to manage natural change more effectively.