Willow Creek, near Willow Waters
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
- No bank erosion or evidence of stock either accessing or damaging the site
Riparian vegetation consisted of native trees and shrubs
About the location
Willow Creek is a small intermittent stream that rises east from Mount Plantagonet in the Southern Flinders Ranges and flows in a westerly direction for about 20 km before eventually discharging into Wonoka Creek around Willow Plains. This stream then drains into Hookina Creek which discharges onto the plain surrounding the eastern side of Lake Torrens. The dominant land use in the 4,558 hectare catchment, upstream from the site, is grazing natural vegetation. The monitoring site was located on a track to Willow Waters off the Hawker to Warcowie Road, about 14 km south from Warcowie and 20 km east from Hawker.
The creek was given a Very Good rating because the site sampled showed evidence of very little changes in ecosystem structure and function, with natural vegetation and habitat features evident throughout the section of stream assessed. There was no obvious evidence of disturbance from stock accessing the dry stream channel but this is likely to change when the stream flows in the future and stock are allowed to use the creek as a watering and feeding location.
The sediments were dominated by boulder, cobble, gravel and detritus, with smaller amounts of bedrock, pebble and sand also present. Samples taken from below the surface were sands and showed no signs that the sediments were recently anaerobic, or lacking in oxygen. No evidence of any bank erosion was recorded and the only sign of animals accessing the banks was from the deposit of kangaroo and emu faeces in places.
At least three types of aquatic plants (Cyperus gymnocaulos, Juncus and Typha) were recorded but there was no evidence of any algal remnants among the dry sediments in the channel. The riparian vegetation was dominated by River Red Gums and acacias over rushes (Juncus) on the poorly vegetated banks (25-49% vegetative cover). The surrounding vegetation at the site comprised low native woodland dominated by wattles, gums and a range of native shrubs.
Special environmental values
Willow Creek is a largely natural, ephemeral stream from the lower rainfall part of the Flinders Ranges, just east from Hawker. Stock grazing is the dominant land use but limited road access to the catchment prevents many of the other types of disturbances that are normally associated with human settlement. No significant environmental values were recorded from the dry site in 2012. However, a range of insects, mites, snails and a few yabbies were recorded from the same location in 1998, so the creek can support a generalist and tolerant aquatic fauna when it is wet.
Pressures and management responses
|Livestock in the catchment are exerting excessive grazing pressure on vegetation, 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: