Not so stupid, Peter. Those points take us to the proposed management
issues discussed in the draft management plan. For ease of access I attach
below at appendix A the description of the present situation at Kelly Swamp,
and at appendix B the proposed management scheme. Kelly Swamp is best seen
as an artificial feature created in its present form following the
realignment of Jerra Creek and the filling of LBG. There is an existing
valve that provides some means to control water levels but this depends on
the level of Jerra Ck/ LBG and has been little used (if at all in recent
years). The question now raised is: if gravity-fed water from Jerra Creek
is available, should this be used to prevent the drying-out of Kelly Swamp,
as now in progress?
That question will divide those who want to see a more-or-less permanent
pond habitat from those who see advantages, practical or ecological, in
periodic complete drying.
I would favour myself a periodic drying but a deepening of the depression in
selected areas (eg around the refuge islands) so that some permanent water
would remain there (subject to gravity-fed availability). The time to
undertake that deepening, and to put in place more dead trees, would be when
conditions are as at present. However, there is, I understand, something
called a PLANNING PROCESS (with an associated BUDGETARY CYCLE, and a WORK
ORDER REQUIREMENT), possibly even NCA APPROVAL. Global warming will be
quicker.
APPENDIX A
Kellys Swamp Water quality and levels are influenced by local rainfall,
floods spilling from the lake and a control valve joining Jerrabomberra
Reach. During high floods the swamp may connect with the adjacent billabong
and floodplain. Habitats vary from an open shallow
pool with periodically exposed gentle shores to dense macrophyte beds,
especially Typha sp. Some large woody debris occurs.
Historic photos from 2002 show fluctuating cover of Azola sp., which may
indicate high nutrient levels. Riparian vegetation is
scattered and consists mostly of introduced willows and poplars. Mounds
planted with native shrubs and trees surround half the
swamp. Exotic grasses dominate the fringing edge and appear to be regularly
slashed. Kellys Swamp provides valuable habitat
for an array of native and migratory birds. Habitats include exposed
mudflats, shallow open water, grassy swamps, large woody
debris, reed beds and other macrophytes. It is relatively protected from
winds and human activity. Experimental sandy shores to
create bird habitat have succumbed to weed invasion over time. Slashing has
replaced historic grazing on the northern portion
of the swamp. A fence divides the wetlands, with the southern portion
appearing to accommodate light cattle grazing. The cattle
would help maintain the mudflat habitat and control grass height.
APPENDIX B
These shallow water areas should be as
large as possible, but no less than 15
metres in width. Locally, islands would
be created, acting as refuge areas,
away from public visitation, and offering
better protection against predation from
cats and foxes. These islands would be
approximately 30-50 square metres in
area and feature stepped terraces on the
margins. The islands would predominantly
offer riparian habitats with sedges, shrubs,
trees and periodic mudfl ats.
. It is proposed that water levels in
the shallow wetlands be managed
and controlled by a series of valves/
gates. This will allow for the temporal
management of mudfl at inundation
and drying, maintenance and selective
isolation of ponds. The water level in the
lake will again infl uence the water levels
in the water bodies as it is necessary that
the shallow wetlands be largely managed
by gravity. Water control in Kellys Swamp
could be managed either by the existing
valve and/or new structures to control
overland fl ow with Jerrabomberra
Billabong. Most appropriate structures
would be confi rmed during the design
of the wetlands using detailed survey
information.
. The maintenance requirement for the
shallow wetlands would be higher than
most other parts of the wetlands. The
limited depth of water, particularly suitable
for macrophyte growth will also tend
to be supportive of algae growth and
Typha species dispersal. This means
that hydraulic residence time (particularly
in summer), associated pumping of
supplementary water, and weeding of
excessive Typha on a regular basis would
be required.
. Periodic drying of these shallow ponds
and/or diversion of fl ushing fl ows through
the system are possible maintenance
options to help clean and refresh the
swamps. Such cleansing actions may be
suitable every 3-5 years or as required to
address poor water quality and aquatic
pests (e.g. weeds and feral fi sh).
Figure 20: Typical Cross-Section of Shallow Pools in Jerrabomberra Wetlands
-----Original Message-----
From: milburn
Sent: Thursday, 24 January 2013 12:37 AM
To:
Subject: Jerrabomberra Drylands!
Its time to roll out that stupid Drylands joke again. The harriers have
switched from the Swamp to the Spotted variety and the collection of
assorted crakes have to sprint in a comedic fashion between that last few
puddles and vegetated cover. The ducks have mostly departed.
Its a shame the water level could not be controlled.
Milburn
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