Drain 56, near Snuggery
2009 Aquatic Ecosystem Condition Report
- Dry drain in autumn and spring 2009.
- Likely to be grossly enriched with nutrients when wet due to the surrounding land uses.
- Aquatic and riparian vegetation absent with only weeds and grasses growing on the banks.
- No evidence of bank erosion.
About the location
Drain 56 is a small drain in the lower South East with a catchment area of about 5 km2. It rises at an elevation about 30 metres above sea level near the Mount Burr Range, receives drainage from Drains 56A and 56D, flows in a southwesterly direction into Drain 54 and ultimately discharges into the English Gap Drain and Lake Bonney SE.
Drain 56 is an artificially constructed drain where the primary function is to remove surface water and draining saline groundwater to improve agricultural productivity in the region (Department for Water 2010). Given its artificial character, the drain is not expected to be in a highly rated aquatic ecosystem condition, although it does provide significant habitat for many aquatic species in the region.
The major land uses are grazing and cropping and historically this drain received wastewater from the Cellulose Mill that closed in 1998. The monitoring site was located near the Princes Highway, about eight kilometres south–east of Millicent.
South East NRM Regional Summary 2009
The drain was given a Poor rating because the site sampled showed evidence of major changes in ecosystem structure and moderate changes to the way the ecosystem functions.There was considerable evidence of human disturbance, including a lack of vegetative cover in the riparian zone and dominance by fine sediments in the channel.
The dry channel of this 10 metre wide drain showed no evidence of being recently wet when inspected in autumn and spring 2009. No macroinvertebrate or water quality data were consequently available for this site.
The sediments were dominated by sand, clay, detritus and gravel; samples taken from below the surface were aerobic and showed no evidence of being anaerobic and blackened, presumably due to the limited time that water has pooled within this drain during the drought in the 2000s.
No aquatic plants were growing in the channel or on the water’s edge, which again emphasised the long time period since water flowed and pooled within this drain.
The narrow riparian zone lacked any native trees, shrubs and other understorey plants, and only weeds and introduced grasses were present. The surrounding vegetation at the site was crop land with no evidence of any remnant native vegetation remaining in the general landscape.
Special environmental features
Pressures and management responses
|Drought||The Drainage Network in the region supports nearly 200 regulators for water conservation and adaptive flows management practices. The freshwater weir pools of some regulators in the Lower South East are now known to support colonies of threatened aquatic species. The South Eastern Water Conservation and Drainage Board has undertaken preliminary investigations to identify additional biological hot spots in the Lower South East, and further investigations may be undertaken. This may lead to the installation of additional regulators to retain water as drought refuge at these key drain locations.|
|Livestock having direct access (causing sediment erosion and adding excessive nutrients).||Drains have been constructed since the 1860s as an engineering solution to support agricultural development and it is South Eastern Water Conservation and Drainage Board practice to lease drain reserves for grazing in certain circumstances. Not all drains are subject to grazing and leases for grazing are only approved following an engineering and environmental assessment. Lease conditions require the lessee to fulfil pest plant, pest animal and CFS management requirements, thereby relieving the Board of these responsibilities.|
|Limited riparian zone vegetation (reducing habitat quality, increasing sediment erosion).||The South Eastern Water Conservation and Drainage Board has undertaken a limited revegetation program at key locations, and has the ability to undertake further revegetation works when resources allow. Revegetation at biological hotspots is recognised as a mechanism to reduce nutrient input and soil erosion, and can be undertaken if it does not impede access for management and maintenance.|
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- Download the brochure for creeks and lakes
- Download the panel assessment information sheet
- Department for Water 2010, South East Water Science Review, Lower Limestone Coast Water Allocation Plan Taskforce, Adelaide.