Rodwell Creek, Woodchester
2008 Aquatic Ecosystem Condition Report
- Significantly affected by nutrient enrichment and fine sediment.
- Severely limited riparian zone invaded by weeds.
- Clearance of native vegetation across the catchment has had a major impact.
- Provides habitat to a threatened fish species.
About the location
Rodwell Creek rises in the southern Mount Lofty Ranges near Archer Hill and flows south-east to Woodchester before discharging into the Bremer River. The stream flows only occasionally through a small catchment area, where livestock grazing is the main land use, along with some horticulture, dairying and urban development.
The site selected for monitoring was located off Wellington Road in Woodchester.
The creek was given a Poor rating at this site because the ecosystem showed evidence of major changes in the animal community and plant life, and moderate changes to the way the ecosystem functions. Very high loads of nutrient and fine sediments were entering the stream from adjacent agricultural land, and the riparian zone was severely affected by human activities.
The creek was dry at the time of inspection in November 2008 and there were no indications that it had flowed recently.
A range of aquatic plants were found in the channel, including Common Reed (Phragmites australis), Sea Rush (Juncus kraussii) and Creeping Monkey-flower (Mimulus repens). Up to 35% of the creekbed was covered with a dried mat of green filamentous algae (Cladophora), and the sediments were mostly grey silt.
There was no evidence of blackened or anaerobic sediments, however sheep manure was found in the channel and there was a moderate amount of bank erosion, caused by livestock entering the stream and occasional flooding.
A few isolated River Red Gums grew along the banks. The riparian zone was less than five metres wide and covered with sparse rushland, introduced pasture grasses and weeds such as fennel, artichokes and oats. The surrounding landscape was virtually treeless, with paddocks used mainly for cereal cropping and grazing.
Special environmental features
Rodwell Creek provides habitat to remnant populations of a threatened fish called the River Blackfish. Some critical pool habitats have been artificially watered in the catchment in recent years to sustain the fish as part of a Drought Action Plan implemented by the Department of Environment and Natural Resources.
Pressures and management responses
|Livestock have direct access at the site and upstream, 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 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.|