Tributary of the Gawler River, Bibaringa
2011 Aquatic Ecosystem Condition Report
- Dry in autumn and spring 2011
- Likely to be enriched with nutrients when wet due to the surrounding land uses
- Riparian vegetation consists of introduced grasses and weeds
About the location
This creek is a small stream in the Southern Mount Lofty Ranges that rises south from Bibaringa and flows in a north-westerly direction where it becomes channelised in Evanston Park and drains into the Gawler River downstream from Gawler township. The monitoring site was located on a track off Kentish Road in Bibaringa. The major land use in the 174 hectare catchment is rural residential living, with smaller areas used for roads, remnant native vegetation and stock grazing.
The creek was given a Poor rating because the site sampled showed evidence of major changes in ecosystem structure, and moderate changes to the way the ecosystem functions. There was considerable evidence of human disturbance including degraded riparian habitats and extensive vegetation clearance in the wider catchment. The site would have rated even poorer if the surrounding well-vegetated hill had been cleared of its remnant native woodland cover.
The sediments were dominated by detritus and clay, with bedrock, boulder, cobble, pebble and sand also present. Samples taken from below the surface were grey in colour and showed no evidence that the sediments were anaerobic or lacked oxygen. No significant areas of bank erosion were seen at the site during 2011.
The dry creek channel lacked any aquatic plants and the presence of terrestrial weeds (artichokes and introduced grasses) indicates that the creek has rarely held water in recent years. The riparian zone lacked any trees or shrubs and consisted of a narrow strip of introduced grasses, artichokes, olives and boxthorn. The surrounding vegetation was largely cleared cropping land with a few scattered gum trees. However, one hill adjacent to the site appeared to have retained most of its original eucalypt woodland cover but included an understorey dominated by introduced grasses.
Special environmental features
Pressures and management responses
|Widespread introduced weeds in the riparian zone at the site and upstream (reducing habitat quality).||The Adelaide and Mount Lofty Ranges NRM Board has several pest plant (weed) mitigation and control programs. They work closely with landholders to control weeds on their property and to help stop the spread to other properties and waterways.|
|Livestock having direct access at the site and upstream (causing sediment erosion and adding excessive nutrients).||The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes incentives for waterway and wetland fencing to exclude or limit stock from entering riparian zones.|
|Limited riparian zone vegetation at the creek and upstream (reducing habitat quality, increasing sediment erosion).||The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes incentives for revegetation programs around waterways and wetlands and stock exclusion as well as educating landholders about the importance of riparian vegetation in managing soil erosion.|
This aquatic ecosystem condition report is based on monitoring data collected by the EPA. It was prepared with and co-funded by the Adelaide and Mount Lofty Ranges NRM Board.