South East NRM Regional Summary
2014 Aquatic Ecosystem Condition Report
Forty sites were sampled in the South East during autumn and spring 2014. These sites were located throughout the region from Bordertown in the north to drains and creeks east from Port MacDonnell in the south.
- Few naturally occurring creeks occur in the region that is dominated by artificially constructed drains which incidentally provide significant habitat for aquatic biota at some locations.
- Sites on creeks and drains near the coastline were generally in better ecological condition compared to the more inland sites.
- Sites receiving point source discharges, urban stormwater or located within heavily cleared catchments rated the poorest in the region.
- Agricultural land uses contribute large loads of nutrients, salt and fine sediment to most drains and streams in the region.
- Nutrient enrichment was affecting most creeks and drains in the region as evidenced by high nutrient concentrations (mostly nitrogen) and large growths of filamentous algae, phytoplankton and/or aquatic plants.
- Riparian zones were generally degraded or largely non-existent, apart from introduced grasses and weeds that were often grazed and damaged by stock accessing the banks.
- Legacy issues associated with the recent drought from 1997-2009 probably contributed to the generally degraded condition of many sites sampled in 2014.
- The most significant biodiversity hot-spots for rare and sensitive aquatic species were Piccaninnie Blue Lake Outlet and Eight Mile Creek located east from Port MacDonnell in the Lower South East.
Two sites were assessed in Good ecological condition, 16 were in Fair condition, 21 were in Poor condition, and one was in Very Poor condition.
The sites that were rated in Good condition included Eight Mile Creek and Piccaninnie Blue Lake Outlet, located in the lower South East between Port MacDonnell and the Victorian border. They are permanently flowing, freshwater streams that rise as groundwater-fed ponds a short distance inland. Eight Mile Creek flows for nearly 4 km from Ewens Pond to the coast and receives additional water from several drains that are designed to alleviate flooding of adjacent dairy grazing and irrigated pasture properties. The Piccaninnie outlet, also called Ellards Creek, was constructed during the 1917 to 1945 period to help prevent local flooding; it only extends a few hundred metres but the entire catchment area now lies within the Piccaninnie Ponds Conservation Park (Department for Environment & Planning 1992). Both sites provided habitat for a range of rare and sensitive aquatic species but showed some of the early signs of nutrient enrichment, including high nitrogen concentrations and notable presence of filamentous algal growths.
The Fair sites were mostly located from small to moderately sized coastal drains and creeks in the region and all showed evidence of moderate nutrient enrichment (e.g. high nutrient concentrations and moderate to large growths of filamentous algae or aquatic plants). They included Picks Swamp Outlet Drain, Deep Creek and Jerusalem Creek in the Port MacDonnell area, several sites from the Reedy Creek drain catchment, Stony Creek draining into Lake Bonney SE, the lower reaches of Drain M, Bray Drain and Drain L near Robe, and Henry Creek located in the Upper South East. These sites lacked many sensitive and rare aquatic species and were dominated by tolerant and generalist macroinvertebrates.
The Poor sites were located from the more salinised and ephemeral catchments throughout the drier inland parts of the region and included a few coastal drains as well. They included sites from Hitchcox Drain in the Lower South East, Drains 31 and 44 draining into Lake Bonney SE, Lake Frome North Drain and Narrow Neck Drain near Rendelsham, the upper reaches of Drain M and Mosquito Creek, Blackford Drain inland from Kingston SE, Marcollat Watercourse and Didicoolum Drain in the Upper South East, and sites from Naracoorte, Nalang and Tatiara creeks in the Naracoorte to Bordertown area further inland. These sites all showed evidence of gross nutrient enrichment, were comprised of tolerant and generalist aquatic species, and many were also affected by high salinity and limited inflows of water.
The only site considered to be in Very Poor condition was Drain 57 downstream from the paper and pulp mill discharge. This site was characterised by excessive nutrient enrichment, poor riparian and aquatic habitats and presence of a sparse range of aquatic macroinvertebrates, despite the presence of permanently flowing freshwater in autumn and spring 2014.
The majority of sites sampled with water present had macroinvertebrate communities dominated by tolerant species and few rare or sensitive species were recorded. The most widespread and commonly recorded species included snails (Glyptophysa, Angrobia, introduced Potamopyrgus and Physiella, and Coxiella at saline sites), mites (Diplodontus and Eylais), amphipods (Austrochiltonia), beetles (Sternopriscus, Necterosoma, Paracymus and Limnoxenus), biting midges (Bezzia), chironomids (Procladius, Cricotopus, Tanytarsus and Chironomus), waterbugs (Microvelia, Sigara, Micronecta, Naucoris and Anisops), damselfly larvae (Austroagrion and Austrolestes), and caddisflies (Hellyethira simplex, Notalina spira and Triplectides australis).
The only regionally rare and sensitive species recorded during 2014 included a new family of amphipod crustacean (Paracalliopidae), Glenelg Spiny Crayfish (Euastacus bispinosus), Swamp Yabbies (Geocharax), blackfly larvae (Austrosimulium furiosum), dixid fly larvae (Dixidae), and a few mayflies (Offadens, Atalophlebia australis and Thraulophlebia inconspicua) and caddisflies (Taschorema complex, Lingora and Atriplectides dubius). Notably, stoneflies and several species of mayflies that were collected from the region during the 1990’s (e.g. Atalophlebia aurata, Ulmerophlebia pipinna and Nousia fuscula) were not detected and may now be regionally extinct; it is likely that the recent extended dry period from 1997 to 2009, in which the lowest rainfall was recorded from South Eastern Australia over the last 110 years of reliable climate data (CSIRO 2010), contributed to the loss of sufficient critical refuge habitat to sustain all the aquatic species that occurred in the region.
The most significant streams in the South East include Eight Mile Creek, Piccaninnie Outlet, Deep Creek and Picks Swamp Drain; each supports a rich assemblage of rare, sensitive and more common aquatic macroinvertebrates, and typically provide habitat for a rich plant and fish assemblage of species. The coastal streams and drains located east of Port MacDonnell to the border also supported paracalliopid amphipods, first noted for the region in 2014, as well as freshwater crabs (Amarinus) and shrimp (Paratya). Flow dependent species were largely confined to these same streams, as well as Reedy Creek-Mount Hope Drain, Stony Creek, Drains 31, 44, 57 and the lower reaches of Drain M. Threatened fish such as Southern Pygmy Perch, Yarra Pygmy Perch and Dwarf Galaxias were also collected from many of the above coastal creeks and drains; nearly half the sites supported Southern Pygmy Perch, which appeared to be commonly collected or seen in spring.
All creeks and drains showed at least some evidence of nutrient enrichment which included high concentrations of nutrients (particularly nitrogen) and the presence of large growths of filamentous algae, phytoplankton, and/or excessive growths of reeds and other aquatic plants. Some sites also had salinity levels well over 3,000 mg/L which generally limits ecological communities to only include the more saline-tolerant types of plants and animals.
Apart from a small number of sites in conservation parks and/or coastal streams that had intact vegetation communities, most sites lacked any significant riparian vegetation and were dominated by introduced grasses and weeds; constructed drains typically lacked trees, shrubs or any native vegetation. Many also had large areas of bare soil and showed evidence of erosion by stock accessing the banks and water directly.
Special environmental features
The climate in the region is typically considered wet, with cool winters and dry, mild to hot summers (Goyder Institute Report). Rainfall tends to increase from north (400-600 mm/year) to south (600-1,000 mm/year), and coastal areas are dominated by winter rainfall whereas more summer rain occurs in inland areas. As noted above, persistent drought across much of the State from 1997-2009 has resulted in many creeks and drains having limited periods of permanently flowing riffle habitats, ceasing to flow for extended periods, or drying to form only isolated pools during summer and autumn; less than ideal conditions for species that require flowing water (particularly in spring), as well as good habitat and freshwater for their continued survival. More recent data from Mount Gambier shows that above average rainfall occurred in the region in 2010, 2011 and 2013 but the intervening 2013 and 2014 years were particularly dry (see Bureau of Meteorology website).
Wetlands once covered an area of about 44% of the South East but drainage and land clearance associated with European settlement of the region has reduced this to less than 6% of their original extent. These changes in land use and hydrology have significantly altered the ecology of the remaining wetlands, resulting in many remaining dry for long periods and salinities increasing to levels that only favour the more saline tolerant plants and animals (Department for Water 2010). The drainage system that has subsequently been constructed in the region covers about 2,515 kilometres of drains, channelised watercourses and creeks. While the primary functions of the drains involve removing surface water and draining saline groundwater to support the continued agricultural productivity in the region (Department for Water 2010), they also provide an incidental but significant habitat for many aquatic species in the region. The coastal streams and drains located east from Port MacDonnell to the Victorian border and those sites described above that support a few flow-dependent species are clearly the most significant aquatic habitats in the region, largely because their number is so limited within a drought affected region.
Pressures and management responses
The management responses in the South East NRM Region are based on the waterway being considered a drain or a creek/river.
|Limited water flow
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.
Through ground and surface water allocation planning and the South East Regional NRM Plan water affecting activity permit process the South East NRM Board seeks to manage water for environmental, social and economic purposes in a range of climatic scenarios.
|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.
The South East NRM Board supports targeted projects that provide opportunities for landholders to access grants for fencing for stock exclusion from time to time for priority catchments.
|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 doesn’t impede access for management and maintenance.
The South East NRM Board assists landholders to access targeted grant opportunities for revegetation and ecosystem protection when funding is available. The Board also works closely with landholders consistent with the Board’s Regional Pest Management Plan to control weeds on their property and to assist in halting their spread to other properties.
|Wastewater discharges, adding excessive nutrients and organic matter (leading to algal growth and aquatic weeds).
SA Water Wastewater Treatment Plants at Millicent and Narracoorte
SA Water assess and undertake scheduled process improvement actions at the wastewater treatment plant, with the aim to reduce environmental risk and ensure operations are compliant with EPA licence conditions.
- Download the brochure for creeks and lakes
- Download the panel assessment information sheet
- CSIRO (2010). “Climate Variability and Change in South-Eastern Australia: A Synthesis of Findings from Phase 1 of the South Eastern Climate Initiative (SEACI).” Report prepared for the South Eastern Climate Initiative Steering Committee.
- Department for Environment and Planning (1002). “Piccaninnie Ponds Conservation Park Management Plan.” National Parks & Wildlife Service, May 1992, Adelaide.
- Department for Water (2010). “South East Water Science Review”, Lower Limestone Coast Water Allocation Plan Taskforce, Adelaide.
- Wear, R.J., Eaton, A., Tanner, J. & S. Murray-Jones (2006). “The Impact of Drain Discharges on Seagrass Beds in the South East of South Australia.” Final report prepared for the South East Natural Resource Consultative Committee and South East Catchment Water Management Board. SARDI Aquatic Sciences Publication No. RD04/0229-3.