South East NRM Regional Summary
2019 Aquatic Ecosystem Condition Report
Locations
21 sites were sampled in the South East during spring 2019. These sites were located throughout the region from Bordertown in the north to drains and creeks east of Port MacDonnell in the south.
Key Points
- Few naturally occurring creeks occur in the region which is dominated by artificially constructed drains. The primary function of the drains is to remove surface water and draining saline groundwater to improve agricultural productivity in the region (Department for Water 2010). Given their artificial character, the drains are not expected to be in a highly rated aquatic ecosystem condition, although they do provide significant habitat for many aquatic species in the region.
- All creeks and drains provide habitat for aquatic plants and animals when wet, and many are significant habitats for aquatic macroinvertebrates and fish in a landscape that has been extensively drained.
- Sites in creeks and drains near the coastline were in better condition compared to more inland sites.
- The best sites were small coastal flowing freshwater creeks in the Lower South East. These included Deep Creek, Eight Mile Creek and Piccaninnie Blue Lake Outlet which were each characterised by the presence of a rich community of rare, sensitive and tolerant macroinvertebrate species.
- Agricultural land uses contribute large loads of nutrients, salt and fine sediment to most drains and streams in the region.
- Nutrient enrichment was affecting all watercourses, as shown by high nutrient concentrations (mostly nitrogen) and large growths of filamentous algae, phytoplankton and/or aquatic plants.
- Riparian zones were generally non-existent or degraded, and comprised introduced grasses and weeds that were often grazed by stock accessing the banks.
- Legacy issues associated with the recent drought from 1997-2009 (eg lowering regional groundwater levels and reducing surface flowing habitats) probably contributed to the generally degraded condition of many sites sampled in 2014 and again in 2019.
Findings
3 sites were assessed in Good ecological condition, 9 in Fair condition, and 9 in Poor condition. No sites were considered to be in Excellent, Very Good or Very Poor condition.
The Good sites included Deep Creek, 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 before discharging through drain-like channels into the Southern Ocean. Deep Creek is a small 2.6-km coastal drain with a catchment area of about 15 km2 which is mostly used for dairy grazing. 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 Blue Lake Outlet, also called Ellards Creek, was constructed from 1917 to 1945 to help prevent local flooding. It only extends a few hundred metres but the entire catchment now lies within the Piccaninnie Ponds Conservation Park (Department for Environment & Planning 1992). Each of these sites provided habitat for a range of rare and sensitive aquatic species but showed some of the obvious signs of moderate to gross nutrient enrichment, including high nitrogen concentrations and large growths of green filamentous algae.
The Fair sites were mostly located from small to moderately sized coastal drains and creeks in the region but also included 2 more inland sites in Mosquito Creek. Each site showed evidence of moderate nutrient enrichment (eg high nutrient concentrations and moderate to large growths of filamentous algae or aquatic plants) but also included a few rare and sensitive aquatic macroinvertebrates among communities that were dominated by generalist and tolerant species. Sites included Picks Swamp Outlet Drain in the Lower South East, Stony Creek near Lake Bonney, Mt Burr-Heath Drain, Narrow Neck Drain, Drain at Bevilaqua, Bray Drain located further north around Southend and Rendelsham, dry Drain M at Callendale, and the 2 Mosquito Creek sites further upstream and south from Naracoorte.
The Poor sites were located throughout the region. They included saline and freshwater coastal creeks and drains such as Hitchcox Drain and Jerusalem Creek in the Lower South East, Drain 44 flowing into Lake Bonney SE, and Reedy Creek-Mount Hope Drain, Drain L, Blackford Drain and Henry Creek further northwards near the coast. They also included inland stream sites on Naracoorte and Tatiara Creeks. These sites all showed evidence of gross nutrient enrichment and supported mostly tolerant macroinvertebrate species, and a few were also affected by moderate to high salinity or lacked flowing water habitats. The site on the Reedy Creek-Mount Hope Drain had also been damaged by a recent pesticide drift event, which caused the death of many yabbies, snails, beetles, waterbugs and terrestrial spiders. Many surviving macroinvertebrates were still alive when sampling was carried out a few days after the chemicals were sprayed to paddocks adjacent to the drain, which suggested that some species and individuals received sub-lethal doses and would hopefully be able to complete their life-cycles and help the affected area of drain recover in the future.
The majority of wet sites had macroinvertebrate communities dominated by generalist and tolerant species and included a few rare or sensitive species. The most widespread and commonly recorded species were snails (Angrobia and introduced Potamopyrgus and Physa at freshwater sites and Coxiella at saline sites), mites (Piona), amphipods (Austrochiltonia, Paracalliopidae, Corophiidae and Austrogammarus), beetles (Limbodessus, Antiporus, Sternopriscus, Necterosoma, Paracymus and Limnoxenus), biting midges (Bezzia and Culicoides), chironomids (Procladius, Cricotopus, Tanytarsus, Paratanytarsus and Chironomus), waterbugs (Microvelia, Sigara, Micronecta, Naucoris and Anisops), damselfly larvae (Ischnura and Austrolestes), and caddisflies (Notalina spira and Hellyethira species).
The only regionally rare and sensitive species recorded during 2019 were the following taxa that frequent flowing freshwater habitats: blackfly larvae (Austrosimulium and Simulium); chironomids (Riethia and Rheotanytarsus), leptophlebiid mayflies (Thraulophlebia pilosa and Atalophlebia species), caddisflies (Lingora aurata, Atriplectides dubius); and a baetid mayfly (Offadens confluens). All Lower South East creeks and drains also supported amphipods from the family Paracalliopidae, which were first recorded from the region from similar sites in 2014.
A number of rare species recorded in 2014 were not seen in 2019, including the Glenelg Spiny Crayfish (Euastacus bispinosus), Swamp Yabbies (Geocharax), dixid fly larvae (Dixidae), mayfly (Thraulophlebia inconspicua) and caddisfly (Taschorema complex). The crustaceans probably still exist in Deep and Eight Mile Creeks and wetland habitats but it is uncertain if the other taxa persist in the region. The continued absence of several other sensitive species that had previously been recorded from the South East during the 1980-1990s, suggests that some may have become regionally extinct. They include mayflies (Atalophebia aurata, Ulmerophlebia pipinna and Nousia fuscula); stoneflies (Dinotoperla brevipennis, Dinotoperla evansi, Leptoperla primitiva and Austrocerca tasmanica) and caddisflies (Triplectides magnus and Triplectides similis). All require frequent flowing freshwater habitats and many are flow-dependent species. It is possible 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 towards the loss of critical flowing freshwater refuge habitat needed to sustain all the aquatic species that previously occurred in the region.
All creeks and drains in the region showed evidence of moderate to gross 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. Blackford Drain also had a salinity level well over 3,000 mg/L which generally limits ecological communities to include only the most saline-tolerant types of plants and animals.
Apart from a few sites in conservation parks and coastal locations that had some intact natural vegetation communities, most sites lacked any significant riparian vegetation and were dominated by introduced grasses and weeds. By design the many constructed drains typically lacked trees, shrubs or any native vegetation to support their primary function to drain the landscape. Many drains and inland creeks also had large areas of bare soil and showed evidence of erosion by stock accessing the banks and the water directly.
Special Environmental features
The climate in the region is typically considered wet, with cool winters and dry, mild to hot summers. 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 while more summer rain occurs in inland areas. As noted above, persistent drought across much of the state from 1997-2009 resulted in many creeks and drains having limited periods of permanently flowing riffle habitats, and 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, 2013, 2016-2018 but the other years including 2019 were generally well below average rainfall years (see Bureau of Meteorology).
Pressures and Management Responses
Pressure |
Management response |
Limited water flow |
Drains The Drainage Network in the region supports nearly 200 regulators for water conservation and adaptive flows management practices. The South East Drainage and Wetland Strategy was released in 2019 which guides the management of surface and drain waters in the South East Region. The strategy promotes the reduction of ocean discharge, the retention of water in the landscape, and the implementation of initiatives to restore inundation of wetlands. |
Livestock having direct access (causing sediment erosion and adding excessive nutrients). |
Drains 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 occupation licences 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). |
Creeks As a part of the Naracoorte Creek and Creekwalk Master Plan 2020 the Naracoorte Lucindale Council in partnership with the SE NR plans to conserve and re-establish large portions of endemic vegetation, and remove many of the pest plant species I and around the creek. As a part of the Tatiara Coorong Local Action Plan, in partnership with the SE NR, the Tatiara Council have developed the Tatiara Creek Report to identify areas of the Tatiara Creek where management actions such as fencing to manage stock, weed control, erosion control and revegetation to improve the condition of the Creek. The Department for Environment and Water has implemented a process to manage impacts of diving in Ewens Ponds including managing numbers and with an annual closure in Spring and have implemented some in pond revegetation works. Early indications are that vegetation is improving in the ponds. Drains The South Eastern Water Conservation and Drainage Board has historically undertaken revegetation 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. |
Chemical drift from agricultural spraying |
The Australian Pesticides and Veterinary Medicines Authority (APVMA) is responsible for assessing the environmental and human health safety from exposure to agricultural and veterinary chemical use and providing label instructions for approved chemicals which outline the conditions associated with using chemicals in the environment in Australia. They also include a spray-drift management website that aims to assist users to apply chemicals and avoid harm to humans and the environment; this includes operating principles, guidelines, manuals, labelling instructions, risk assessment and management tools, and standard scenario information for boom sprayer, fixed wing and helicopter operators (see https://apvma.gov.au/node/10796). In South Australia, Primary Industries and Regions SA (PIRSA) is responsible for regulating agricultural chemical use and investigating alleged chemical misuse issues. This includes:
PIRSA should be notified of such issues by contacting the Agricultural and Veterinary Chemicals Hotline (Phone 1300 799 684) or email: PIRSA.RuralChemicals@sa.gov.au (see https://www.pir.sa.gov.au/biosecurity/rural_chemicals/reporting_and_communications). Additional educational information relating to chemical use best practices is also included on PIRSA’s website which includes consideration of prevailing weather conditions, following label instructions, record keeping and links to codes of practice (see https://www.pir.sa.gov.au/biosecurity/rural_chemicals/chemical_use_best_practice). The more significant spray drift issues that cause potential or actual environmental harm, particularly involving waters, may also involve an investigation relating to any breaches of the Environment Protection Act 1993 (https://www.epa.sa.gov.au/data_and_publications/legislation). Consequently, the Environment Protection Authority (EPA) may liaise with PIRSA on more serious cases involving chemical drift and monitor and assess environmental harm, and take further regulatory action if it is appropriate (eg warnings, environment protection orders, prosecutions). |
Wastewater discharges, adding excessive nutrients and organic matter (leading to algal growth and aquatic weeds). |
SA Water Wastewater Treatment Plants at Millicent and Naracoorte SA Water investigates reuse opportunities and assesses and undertakes scheduled process improvement actions at the wastewater treatment plants, with the aim to reduce environmental risk and ensure operations are compliant with EPA licence conditions. |
Further Information
- Brochure for creeks and lakes
- Panel Assessment Report (2019) for the South East NRM Region
- 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 1992, 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 RJ, 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.