Home' My Ballarat : July 2011 Contents City of Ballarat Community Magazine July 2011
Lake Wendouree update
For the first time since the summer of 2003 lake weed will be harvested
across the entire 123 hectare area of Lake Wendouree, with cutting due
to be completed by September in time for the start of the aquatic sports
Council recently awarded two contracts for the work which will see up to four
harvesters used to cut the lake weed. Around 300 cubic metres of weed,
weighing in at around 40 tonnes, will be cut each day.
Members of the public wanting to use lake weed for garden compost can pick
it up free of charge from Victoria Park, in Gillies Street, opposite Council’s
Cr Judy Verlin, Growth and Development Portfolio Councillor, says the work will
ensure that rowers and sailors in particular can begin their season unhindered
by the heavy growth of aquatic plants which have been a problem since
water returned to the lake.
“This is a positive sign that things really are returning to normal”.
Prior to the lake dr ying out, the lake weed was harvested annually to allow
the smooth passage of boats and water craft.
With the rapid return of water and re-colonisation of the Lake in recent
months Council has undertaken restricted harvesting. Independent ecological
advice was that the risk of large algal blooms would increase if large scale
har vesting of aquatic plants from the Lake was allowed during its initial
re-filling phase. Aquatic plants consume and store nutrients introduced into
the lake by storm, ground and recycled water, which otherwise would be a
food source for algae.
Works are again underway and the contractors have brought in additional
equipment to hasten the dredging rate to ensure the work is completed
ahead of the coming spring season.
The dredging is taking place along 1750 metres of the rowing course,
deepening it by 0.5 metres. The sediments collected from the dredging are
being deposited within two of the existing reed beds to create permanent
shallow wetlands. Deepening the rowing course will mean that Lake Wendouree
will meet all national rowing competition standards. It will also ensure that
if water levels drop again, there will still be sufficient depth for training and
state standard regattas, safeguarding the sport against future drought and
extremes of weather.
Since the Lake filled, supplies of recycled water, ground water and diverted
storm water have ceased and it is unlikely that these sources will need to
be drawn upon in the near future, as Council is aiming to maintain the Lake
level between 10 and 12 cm below full. This will allow dredging to continue
The dredging of the rowing course has experienced delays due to the floods
and consequent unexpected filling of the Lake. Once the Lake exceeded its full
level, works were suspended until a normal water level could be regained.
Managing the water levels
An additional weir gate structure has been installed at the Lake to regulate
water levels by slowly releasing water after large storm events. Prior to this
installation only one outfall was operating, a bi-wall structure located on
the eastern shore. Council is confident that the new weir gate will allow for
sufficient water to be released so that the surrounding storm water system
can cope with heavy rain fall.
The Lake level can be observed at two locations. One marker is positioned
on the bi-wall structure opposite Devon Street, and the other at the end of
the Isthmus near the Olympic Precinct.
These two gauges have been adjusted following resur veying to ensure they
are set at the same level.
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