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Stormwater
Treatment Facilities |
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Sediments and nutrients carried by stormwater
runoff can impact greatly on Lake water quality
and ecosystem health.
Stormwater Treatment Facilities
aim to reduce the impact of sediment and nutrients
by mimicking natural systems and are a preferred
alternative to traditional concrete drainage
lines.
There are different types of Stormwater Treatment
Facilities including:
- Constructed wetlands
- Detention basins
- Sediment or silt traps
- Gross pollutant traps
- Vegetated swales
- Riffle ponds
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Foreshore
Stabilisation / Vegetation |
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Foreshore and creek
banks form a key part of the Lake’s estuarine environment. These
areas provide recreation opportunities for residents
and important habitat for wildlife. Residential
development along creek fronts and foreshore
land can result in a loss of native vegetation,
accelerated bank erosion, and increased volumes
of runoff containing sediment and nutrients.
Revegetation of foreshores
and creek banks are accompanied by many different
stabilisation techniques including the use
of rock and small pebbles, and reshaping the
foreshore/creek bank to a natural sloping beach. The
use of small pebbles along the natural sloping
beach allows dead seagrass wrack to wash out
of the water and decompose naturally. |
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Maintenance
Dredging |
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| Maintenance dredging is the dredging or removal
of bed sediments to return the area to a similar
level to what previously existed. It refers primarily
to the removal of delta plumes or fans at the end
of stormwater lines entering the Lake. This accumulation
of sediment smothers and prevents seagrasses from
growing. It can also refer to the dredging of shoals
in the main navigation channel. |
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Wetland
Rehabilitation |
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Wetlands are an important part of the aquatic
ecosystem as they provide a natural filter system
for our water, trap sediment and decrease nutrients
and pollutant from entering Lake Macquarie and
provide habitat, protection and important nursery
areas for aquatic animals.
Wetlands are amongst the
most threatened ecosystems. Around
35% of Lake Macquarie’s wetlands have been
lost and 70% of Lake Macquarie wetlands have
been found to have reduced in size over the last
five years.
Wetland rehabilitation
undertaken by the Office of the Lake Macquarie
and Catchment Coordinator has involved weeding,
planting and bush regeneration, along with
rubbish removal, fencing and signage. Lake
Macquarie wetlands that have been rehabilitated
include:
- Boat Harbour Wetland, Silverwater
- Pelican Wetland, Pelican
- Beauty Point Wetland, Dora Creek
- Galgabba Point wetland, Swansea
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Nearshore
Organic Sediment Removal and Foreshore Improvement |
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Many shallow embayments
around Lake Macquarie contain vast seagrass
beds. While these
seagrasses provide enormous value to the ecology
of the lake, they can cause problems around the
foreshore when the plants shed their leaves or
fronds. The fronds typically wash up onto
naturally sloping foreshore as wrack, where it
then decomposes rapidly.
Where vertical seawalls or escarpments have
replaced most of the naturally sloping foreshore,
the seagrass wrack accumulates and breaks down
underwater to form oozy organic sediment.
The aim of Nearshore Organic
Sediment Removal and Foreshore Improvement
is to enhance the natural lake processes occurring
around the shore and provide a better environment
for all. The
works involve the removal of nearshore organic
sediment using an excavator, followed by the
placement of sand and/or cobble to re-establish
a gently sloping beach foreshore to reduce the
likelihood of the organic sediments returning
in the future as seagrass wrack can to wash up
on the shore and decompose naturally. |
