Unnamed creek, 2.5 km south-west from Tunkalilla
2011 Aquatic Ecosystem Condition Report
- Dry in autumn and spring 2011
- Likely to be enriched with nutrients when wet due to the extent of cattle grazing in the local catchment
- Riparian vegetation included a few trees and shrubs over a range of swampy marshland aquatic plants
- Moderately eroded banks due to cattle accessing the creekbed
About the location
This Unnamed Creek near Tunkalilla is a small, first-order stream in the Southern Mount Lofty Ranges that rises east from Deep Creek Conservation Park and flows in a southerly direction before discharging onto Tunkalilla Beach in the Southern Ocean. The monitoring site was located off Eric Road, about 3 km east from Tapanappa Hill on the Fleurieu Peninsula. The major land use in the 36 hectare catchment is stock grazing, with small areas used for a road and conservation.
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, bank erosion and anaerobic sediments.
The 12 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 and clay, with some silt and sand also present. Samples taken from below the surface were black in colour and had a strong manure odour, indicating that the sediments were anaerobic and lacked oxygen. Over 10 m of bank showed evidence of erosion due to cattle accessing and damaging the creek.
Aquatic plants covered over 65% of the channel and included large growths of sedges (Baumea) and rushes (Juncus), and smaller patches of cumbungi (Typha) and waterbuttons (Cotula).
The riparian zone extended 10-30 m from the edge of the creek and was dominated by a marshland assemblage of sedges, rushes and grasses, with a few trees and shrubs present. The surrounding vegetation was cleared grazing land with only a few isolated trees present in the local landscape.
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.|
|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.