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The Lake Mokoan Project is not just about the Lake itself.
The project involves making other environmental improvements
such as environmental flows for the region's rivers, the
rehabilitation of the wetlands and careful environmental
management in order to conserve the natural environment,
its flora and fauna. |
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Highly Degraded Lunette Woodland |
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Wetlands are important because they provide habitat for a diverse
range of flora and fauna. A variety of habitats are created as
a result of the continuous flooding and drying. As water levels
rise and fall, habitats change. This in turn encourages diversity
amongst both flora and fauna.
Lake Mokoan currently attracts a variety of flora and fauna
(see species listed). Although there is an abundance of flora
and fauna, some of which is of high significance, its distribution
is limited. There are large areas of little to no native speices.This
is because exotic species, such as phalaris, out-compete native
vegetation.
The native vegetation in the area surrounding Lake Mokoan has
been depleted since European settlement. Vegetation is fragmented
and a significant proportion is classed as endangered. The rehabilitation
of Lake Mokoan will provide important links for fragmented and
endangered vegetation in the region.
Some flora and fauna species have a National and/or State conservation
status (Vulnerable to Extinct). This is outlined in the Environment
Protection and Biodiversity Conservation Act 1999 (National)
and the Flora and Fauna Guarantee Act 1988 (Victorian). Several
species of National and State conservation status can be found
at Lake Mokoan. Assessments are being conducted according to
Federal and State legislation to determine the impacts of decommissioning
on these species.
Animal habitat is reliant on water quality and quantity. Blue
green algal blooms have been frequent at Lake Mokoan. Turbid
water from increased sediment loads has also affected the water
quality of the Lake. These are issues, which need to be tackled
locally and on a catchment wide basis. The extent of the catchment
will depend on the origins and flow paths of surface water into
Lake Mokoan.
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Submerged Aquatic Hebland
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Healthy rivers are the lifeblood of Victoria, the region's
community, economy and the environment. Natural flow variability
is the key to maintaining river and floodplain health. Many
important flora and fauna are reliant on rivers and waterways
for breeding and food resources.
The Broken River has high environmental values, providing
habitat for several significant species such as the Murray
Cod. Murray Cod habitat is under threat due to siltation
of the streambed, clearing of native vegetation and the
introduction of cattle on the river bank. The regulation
of rivers and waterways with dams and weirs has impacted
fish passage. The removal of Lake Mokoan from the Broken
River system, which includes dams and other structures,
will result in more natural variable flows into the river
system.
The condition and habitat of the Broken River will improve
with increased flows, better water quality and revegetation
of riparian zones and floodplains.
For more information regarding River Health click
here
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Red Gum Swamp
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Pest Plants and animals
Pest plants and animals can have a major impact on the environment,
both within and surrounding the wetland. There are a number of
management techniques available to reduce the incidence of these
pests. Generally, an integrated approach with a wide variety of
control techniques must be taken. Management must also involve
surrounding land managers for them to be effective.
One major pest plant within the Lake Mokoan area is Phalaris.
Phalaris is a tall, robust tussock grass, which can be invasive
in areas containing native grasses. Animals, soil, machinery,
vehicles and water spread the seed of Phalaris. The basal parts
of the tussock may be broken up and spread in earth moving or
cultivation. Control techniques include grazing, spraying, slashing
and burning. An integrated control program will be trialed and
utilised to control phalaris and other pest plants within the
rehabilitation area.
Water Quality
Catchment run-off can carry a variety of pollutants including
fertilisers, sediments, animal manure and pesticides. This pollution
flows into wetlands, rivers and waterways, and can cause mass
destruction to native flora and fauna. It is important therefore
to prevent these contaminants from entering wetlands, rivers
and waterways. Wetlands provide an important function as a filter
of sediment and nutrients. However excessive nutrient or sediment
loads can be detrimental to the habitat provided by wetlands,
such as reduced dissolved oxygen in the water and algal blooms.
Figure 1 shows the pathways of sediment and nutrients in the
wetland.
Lake Mokoan has been subject to a number of algal blooms caused
by increased nutrients, namely phosphorus. Reducing the amount
of phosphorus entering waterways will improve water quality
and environment health. Increased nutrient levels in waterways
are caused by run off from fertilised land. A number of ways
in which to reduce nutrients such as phosphorus entering the
waterways include:
- Buffers - riparian vegetation around waterways are
important as they slow down the velocity of surface water,
allowing plant uptake of nutrients.
- Best management practices - best management practice
includes timing of fertiliser applications.
- Restricting Stock - Restricting stock access to waterways
will also lead to reduced phosphorus from animal effluent.
Lake Mokoan has also suffered from high sediment loads, which
can suffocate aquatic organisms. By returning Lake Mokoan to
a natural wetland, sediments will be filtered from the water
cycle. This filtration of sediments will improve water quality
and river health downstream. As the wetland dries, sediments
are exposed, dried and blown by the wind, effectively de-silting
the wetland. Management for reducing sediments entering the
wetland and waterway system include:
- Restricting Stock - Restricting stock from waterways
will reduce river bank erosion.
- Control of soil erosion - utilising control measures
to prevent and control various forms of soil erosion, such
as gully or sheet erosion.
- Buffers - riparian vegetation around waterways are
important as they allow the removal of sediments by vegetation.
For more information on river health and water quality please
refer to the GB CMA website www.gbcma.vic.gov.au
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