SA Murray–Darling Basin NRM Regional Summary
2008 Aquatic Ecosystem Condition Report
About the location
A total of 13 sites were sampled along tributary streams that drain into Lake Alexandrina and the lower River Murray in spring 2008.
- Nutrient enrichment and fine sediments were affecting most streams as a result of agricultural practices in the region.
- Finniss River catchment provides a critical refuge habitats for many rare and sensitive species.
- Limited riparian vegetation throughout the region, especially along the drier, ephemeral streams.
Every site showed evidence of nutrient enrichment in the form of extensive algal growths, excessive amounts of aquatic plants or degraded sediments, including eight sites which were dry when inspected.
Two sites on Tookayerta Creek were given a Good rating because their ecosystems showed relatively minor changes to animal and plant life. There were clear, emerging signs of nutrient enrichment as a result of reduced flows in the catchment during the current drought, however the creek continued to support a wide range of sensitive and rare species of macroinvertebrates among mostly slowly flowing habitats in the upper to mid reaches.
The other streams were all assigned a worse condition grade due to a combination of reduced flow patterns, higher salinity levels and poorer habitat.
Seven sites located in higher rainfall areas of the southern Mount Lofty Ranges were assigned a Fair rating because their ecosystems showed moderate changes to animal and plant life, and some changes to the way each ecosystem functioned. There was evidence of human impact, including nutrient enrichment and the presence of large amounts of fine sediment in Mount Barker, Meadows, McHargs and Bull creeks. Gould, Baker and Nairne creeks were dry but also showed evidence of nutrient enrichment.
The other four sites were sampled from Reedy, Preamimma, Rodwell and Harrison creeks and were located in the rain shadow of the Mount Lofty Ranges where the annual rainfall is around 300 mm. They were assigned Poor ratings because their ecosystems showed evidence of major changes in the animal community and plant life, and moderate changes to the way the ecosystems functioned due to limited flow, high salinity and nutrient enrichment. Reedy Creek had high nutrient and salinity levels and its banks were heavily invested with weeds. The other three sites were dry but showed either considerable evidence of nutrient enrichment or the riparian zones were extensively degraded.
Special environmental features
The most biodiverse and significant catchment in the region is the Finniss River which includes the tributary streams of Tookayerta, Nangkita and Meadows creeks. Many rare and sensitive species of macroinvertebrates and fish occur at many locations throughout the creeks and river in this catchment, including numerous mayflies, stoneflies and caddisflies, a rarely-found dipteran larvae, Southern Pygmy Perch, Mountain Galaxias and River Blackfish.
Parts of the Angas River provide habitat for several threatened fish species and rarely seen macroinvertebrates. Scattered remnant pools in the upper Bremer River and Reedy Creek catchments also support rare fish species such as Mountain Galaxias, despite the generally poor condition of these streams.
Pressures and management responses
|Livestock have direct access to some creeks, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds).
|The SA Murray–Darling Basin NRM Board acknowledges the significant impacts that livestock have on aquatic environments and seeks to provide free technical advice and incentives to land managers for fencing and other works as funding permits. Funding incentives are limited in value and extent and require land managers to volunteer to be involved.
|Limited riparian vegetation at some creeks, 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 NRM Board therefore provides free technical advice on a range of topics for land managers and various incentives for works as funding permits.
|Insufficient natural water flows in some creeks resulting from water extraction and climate variability (reducing ecological integrity.
For creeks located in the Eastern Mount Lofty Ranges, the SA Murray–Darling Basin NRM Board is working with the Department for Water and the community to develop a Water Allocation Plan and licensing system which aim to balance social, economic and environmental needs for water. The objective for providing water to the environment is to maintain and/or restore self-sustaining water-dependent ecosystems which are resilient in times of drought.
For creeks located in the Marne Saunders catchment, a Water Allocation Plan and licensing system has been developed.
For those sites not included in a Water Allocation Plan, the Board’s Regional NRM Plan sets limits for new dam construction through the water affecting activity permits section. The dam capacity limits aim to keep new dam development within sustainable limits.
|Widespread introduced trees and weeds in riparian zones (reducing habitat quality).
|The SA Murray–Darling Basin NRM Board recognises the limitations of available funds relative to the scale of the degradation caused by introduced trees and weeds. It provides free technical advice and community education to assist land managers in dealing with the integrated management of aquatic weeds. The NRM Board also has a targeted process, as directed by state government, to strictly prioritise its investment in weed control activities as funds are limited. It actively seeks funding opportunities for weed control; most of which are for locations where biodiversity outcomes can be achieved.
|Saline groundwater inflows to some creeks (reducing ecological integrity).
|Saline groundwater inflows may be exacerbated by two things; vegetation clearing and resultant increase in rainfall recharge, or the extraction of surface water reducing the dilution factor in natural saline discharge zones. The SA Murray-Darling Basin NRM Board’s Land Management Program strategically invests in salinity ‘hotspots’ by providing incentives to land managers to plant perennial pasture/fodder crops or revegetation to reduce recharge. The NRM Board works with various agencies to minimise any further vegetation clearing which may impact on the catchment’s water balance. The NRM Board seeks to manage and provide for environmental flows to allow natural dilution of saline waters through the development of Water Allocation Plans and Water Affecting Activity policies across the region.
|Stormwater runoff from some urban areas causing high water velocities, containing nutrients and sediments (causing habitat disturbance, algal growth and aquatic weeds).
|The SA Murray–Darling Basin NRM Board is working closely with local government through various projects including: Strengthening Basin Communities, funded under the Water for the Future Program to develop Integrated Water Management Plans; the implementation of Water Sensitive Urban Design principles in development planning and conditions; encouraging the implementation of Best Practice Stormwater Management Guidelines. The NRM Board also administers the statutory requirements of the NRM Act relating to Water Affecting Activities.
|Large nutrient inputs from numerous diffuse sources in some catchments (leading to extensive growth of algae and aquatic weeds).
|The SA Murray–Darling Basin NRM Board’s Land Management Program provides free technical advice and education to land managers to minimise fertiliser, manure, or effluent sources of nutrients. The NRM Board also works closely with local government and developers to pursue industry best practice and manage sediment loads entering waterways. The Water Allocation Planning and Water Affecting Activities policies of the NRM Board also seek to minimise nutrient inputs and allow for natural flows to dilute naturally occurring nutrient loads in waterways.
|Extensive aquatic weed growth in some creeks (reducing ecological integrity).
|The SA Murray–Darling Basin NRM Board provides free technical advice and community education to assist land managers in dealing with the integrated management of aquatic weeds. The also has a targeted process, as directed by state government, to strictly prioritise its investment in weed control activities as funds are limited. The NRM Board actively seeks funding opportunities for weed control; most of which are for locations where biodiversity outcomes can be achieved.
|Wastewater discharges to some creeks, adding excessive nutrients and organic matter (leading to algal growth and aquatic weeds).
Mount Barker Community Wastewater Management System
Bird in Hand Wastewater Treatment Plant
SA Water assesses and undertakes 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.
The SA Murray–Darling Basin NRM Board works with local government, SA Water and other agencies to encourage the development of reclaimed water for more appropriate uses.
|Feral predatory fish in some creeks (trout and redfin) (reducing ecological integrity).
|Local volunteer groups are undertaking works at some sites. The SA Murray–Darling Basin NRM Board opportunistically removes pest fish during monitoring activities. Other agencies are responsible for the control of pest fish and have undertaken some awareness-raising activities throughout the region.