Tributary of Waterfall Creek, near Roslyn Heights
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 limited to introduced grasses, weeds and a range of native understorey plants
- Bank erosion evident due to stock accessing the creek
About the location
Tributary of Waterfall Creek is a small stream in the Southern Mount Lofty Ranges that rises south from Mount Hayfield and flows in a NNW direction into Waterfall Creek, which ultimately discharges into Yankalilla Creek. The monitoring site was located near ‘Rosyln Heights’ off Range Road, about 4 kilometres west from Parawa on the Fleurieu Peninsula. The major land use in the 29 hectare catchment is stock grazing, with smaller areas used for cropping and roads.
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 nutrient enrichment, degraded riparian habitats and bank erosion.
The 10 m wide creek was dry in both autumn and spring 2011. No macroinvertebrate or water quality data was consequently available for this site.
The sediments were dominated by detritus, clay, silt and sand. Samples taken from below the surface were grey/black in colour, had a strong manure odour and were sulfidic, indicating that the sediments were anaerobic and lacked oxygen. Over 10 m of bank showed signs of erosion due to cattle accessing and damaging the bed and edges of the creek.
Large growths of emergent aquatic plants (Juncus and Rumex) covered more than 65% of the channel. The riparian zone lacked any trees and consisted of introduced grasses, weeds, bracken, rushes and sedges. The surrounding vegetation was cleared grazing land with a row of pine trees lining a fence-line along one side of the creek.
Special environmental features
Pressures and management responses
|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.|
|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.|
|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.