Diverse macroinvertebrate community dominated by species tolerant of pollution.
Creekbanks severely eroded.
Catchment provides habitat for a threatened native fish species.
Area map
About the location
Mount Barker Creek rises on the outskirts of Mount Barker in the southern Mount Lofty Ranges. It flows eastwards for about 16 kilometres, through the town and then across mainly agricultural land used for sheep grazing and cereal cropping, and discharges into the Bremer River near Callington. The creek receives discharges from the Mount Barker Community Wastewater Management Scheme (via overflow from the Laratinga wetlands) and the Bird In Hand Wastewater Treatment Plant via Dawesley Creek.
The site selected for monitoring was located off Callington Road, upstream from where the creek flows into the Bremer River, about two kilometres south of Callington.
The creek was given a Fair rating at this site because the ecosystem showed evidence of moderate changes to animal and plant life, and some changes to the way the ecosystem functions. Human activity was contributing to nutrient enrichment and widespread erosion along the banks.
Findings
The creek was a series of deep, connected pools when sampled in spring 2008. A diverse community of 48 species of macroinvertebrates was collected, including moderate numbers of chironomids (Procladius, Paratanytarsus and juvenile Chironominae) and smaller numbers of crustaceans, mites, molluscs, worms, flatworms, cnidarians and nematodes. The majority were species able to thrive in high nutrient waters; no sensitive or rare species were collected.
The water was moderately fresh (salinity of 1,365 mg/L) and moderately well oxygenated (58% saturation). It was slightly turbid (or cloudy) and carried moderate to high levels of nutrients such as nitrogen (0.95 mg/L) and phosphorus (0.04 mg/L).
Large growths of green filamentous algae (Cladophora and Spirogyra) were found at the bottom of the pools. Common Reeds (Phragmites australis) and club-rush (Bolboschoenus) lined the edges of the stream.
A mix of detritus, silt, sand and algae made up the creekbed. The sediments were blackened and anaerobic, indicating too much organic material had entered the creek. Up to 50% of the banks showed evidence of erosion caused by livestock having direct access to the creek.
River Red Gums lined both banks, growing over reeds, lignum, and introduced plant species such as olives, fennel and pasture grasses. Surrounding areas beyond the riparian zone were mostly covered by cereal crops, with only a few native plants.
Special environmental features
The creek provides habitat for several uncommonly collected mites (Arrenurus, Halacaridae, Hygrobatidae, and Oxidae). A threatened native fish called the Mountain Galaxias (Galaxias olidus) also occurs in the catchment (H. Hammer, Aquasave Consultants, 2009).
Pressures and management responses
Pressures
Management responses
Limited riparian zone vegetation at the site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).
The SA Murray–Darling Basin NRM Board recognises that the management of riparian vegetation requires a long-term, integrated approach to achieve ecosystem benefits. The board therefore provides free technical advice on a range of topics for land managers and various incentives for works as funding permits.
Wastewater discharges, adding excessive nutrients and organic matter (leading to algal growth and aquatic weeds).
The SA Murray–Darling Basin NRM Board works closely with local government and encourages the development of reclaimed water for more appropriate uses. Mount Barker Community Wastewater Management System Plans are being developed by the District Council of Mount Barker to minimise the discharge from the Community Wastewater Management System by significantly increasing reuse opportunities. Bird in Hand Wastewater Treatment Plant 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.
Observed Condition
Expected Condition
