Wirreanda Creek, near Springfield
2012 Aquatic Ecosystem Condition Report
- Dry in autumn and spring 2012
- Likely to be enriched with nutrients when wet because the catchment is grazed by stock
- Evidence of bank erosion caused by stock damage and prolonged drought in the region
- Riparian vegetation consisted of a sparse cover of gums over native shrubs and understorey species
About the location
Wirreanda Creek is a large, intermittent stream in the Southern Flinders Ranges that rises south-east from Cradock and flows in a westerly direction, where it eventually discharges into Willochra Creek near Particoona. The only land use in the 34,832 hectare catchment, upstream from the site sampled, is grazing natural vegetation. The monitoring site was located at the water reserve near ‘Springfield’ off a track from the Wilson-Cradock Road, about 8 km west from Cradock and nearly 20 km south from Hawker.
The creek was given a Fair rating because the site sampled showed evidence of moderate changes in ecosystem structure, and some changes to the way the ecosystem functions. There was evidence of human disturbance due to stock accessing and damaging the banks but the stream still provided a range of coarse and fine sediment types and supported a range of native and introduced plants in both the riparian zone and surrounding landscape.
The sediments were dominated by pebble, cobble, bedrock and sand, with smaller amounts of boulder and gravel also present. Samples taken from below the surface were sands, and showed no signs that the sediments were recently anaerobic, or lacking in oxygen. Over 50 m of bank showed signs of significant erosion caused by sheep accessing the edges of the stream.
No aquatic plants or evidence of any dried algal deposits were recorded from the dry creekbed. The riparian vegetation was dominated by scattered gum trees over acacias, eremophilas, daisies and grasses. The surrounding vegetation at the site was sheep grazing land dominated by wattles, eremophilas, daisies and chenopods.
Special environmental values
Wirreanda Creek is an ephemeral stream in a relatively flat, low rainfall part of the Southern Flinders Ranges, and had no significant environmental values when it was assessed as a dry site in 2012. Previous sampling of the same site in 1998 recorded a range of aquatic species from the shallow, freshwater, rain-filled pools that were present. They included two non-insect groups (a mite Hydrachna and amphipod crustacean Austrochiltonia) and a sparse assemblage of temporary pool insects such as springtails, beetles, waterbugs and various types of flies.
Pressures and management responses
|Livestock have direct access at the site and upstream, causing sediment erosion and adding excessive nutrients to the watercourse.||
The Northern and Yorke Regional NRM Plan has the following Resource Condition Targets:
Natural Resources (Northern and Yorke) has also been updating its understanding and management of the Willochra Catchment: