in aquatic flora and large in size, this Swamp has undisputed ecological
value with first class assemblages of native species in parts. However,
diversity and abundance of native flora in large areas of the Swamp
have been and continue to be seriously reduced and harmed by many
human activities in and surrounding the Swamp." (Sainty 1997)
to Geoff Sainty of Sainty and Associates, the two largest and most
important impacts on the swamp have been:
Drains cut through Swamp
Extraction of Peat
cut through Swamp
To reduce unhealthy wet conditions for cattle. To improve
potential for grazing. To reduce stock disease. To open up land
for farming. To bring water through the Swamp for human use. To
improve access to remove peat (drains were cut at close spacing
in the area immediately to the south west of the peat extraction
Increase in speed of surface flow through the Swamp.
More rapid dispersal of weed seeds and weed propagules
through the Swamp. Lowering of water quality by "short-circuiting"
around the Swamp (i.e. water is not forced to spread right across
the Swamp but allowed to follow a drain).
drains and redirecting flow more evenly across the Swamp.
The small, surface extraction (downstream of the current
extraction pool) left scars that have only partially revegetated
after many years. The present large scale operation has left a
deep pool (down to about four metres), containing turbid
water with poor aquatic plant diversity. The deep pool has altered
the water flow through the Swamp; upstream has become drier and
downstream wetter. There is increased speed of movement of weed
seeds and propagules downstream by dispersing them across the
extraction pool. Increased spread of aquatic weed into the mid
region of the Swamp by the introduction of machinery carrying
weed seeds and pieces (agricultural or construction machinery
and boats contaminated with weed seeds/pieces is one major reason
for accelerated aquatic weed problems in wetlands). None of the
surface vegetation cleared from the peat has been effectively
returned to the site; this has created an aesthetic imbalance
in a swamp that had little open water.
There is little that can be done to fully rectify the
problem. The pool is too large to back fill, and if it was filled
with material other than peat it would alter the Swamp sub-surface
hydrology. It is too deep to revegetate with emergent species.
It contains water that is evidently unsuited to many submerged
plants. Once recirculation from the peat process is stopped water
quality in the extraction pool may improve, and some "aquatic
life" may return. The edges could be sloped and planted with transplanted
aquatic vegetation but this would create a major disturbance,
being difficult to physically achieve, and based on the slow regrowth
in the shallow peat extraction area downstream, would be slow
peat has changed the hydrology of the Swamp immediately upstream
and downstream of the extraction pool, and this can be judged by
the vegetation in the vicinity. The larger and longer the extraction
pool becomes, the more impact on upstream and downstream vegetation.
mining pool is not a healthy place for floating, submerged and emergent
macrophytes and algae; it contains
none or few of the expected native aquatic plants. The depth and
shape created by the present peat mining operation, and the poor
water quality for aquatic life caused by mining disturbance and
recirculation from processing, makes it difficult to restore. No
serious attempt has been made to restore the peat excavation pool.
island within the peat pool is partly overrun by Willow Salix cinerea
(identification subject to confirmation from flowering material)
and this infestation is probably a source of spread to the rest
of the Swamp. This species of Willow has produced fertile seeds
elsewhere in the Sydney region; it is probable that it is setting
seed in the Swamp as juveniles are scattered throughout much of
the western end.
peat excavations to the south-west of the main excavation pool have
been slow to regenerate surface aquatic vegetation, and serve as
an example of the poor regenerative capacity of exposed peat after
of peat in the future may be retarded by weed invasion introduced
weeds will not necessarily produce peat of the same quality and
of mining is already significant and any increase in the size of
the pool created by peat extraction will only further add to the
decline of the Wingecarribee Swamp ecosystem. The proposed 7 ha
extension to the north west of the present extraction pool will
destroy a reasonably good mixture of primarily native vegetation;
it will direct the flow even more rapidly to the north west side
of the wetland, and cause the area immediately east of the extraction
pool to become even drier.
the Swamp has significant areas with a good assemblage of native
plants, but it also has large areas in a moderate to advanced state
of change from native to exotic vegetation. The peat extraction
pool is poor in macrophytes and
and Associates, Wingecarribee Swamp: Aquatic Vegetation Condition
(Health) Restoration Issues, May 1997, pp. 2-3, 8-9.