Skillogallee Creek, near Auburn
2008 Aquatic Ecosystem Condition Report
- Severely affected by nutrient enrichment, sediment and prolonged drought.
- Macroinvertebrate community dominated by species tolerant of pollution.
- Streambanks and riparian zone damaged by livestock and erosion.
About the location
Skillogallee Creek is a small stream in the Mid North of the state. It rises east of Watervale in the Clare Valley, and flows south into the Wakefield River about seven kilometres southwest of Auburn. Livestock grazing, cereal cropping and vineyards are the main land uses in the catchment.
The site selected for monitoring was located in the lower reaches of the creek, next to a pipeline off Goodonga Road, about six kilometres southwest of Auburn.
Northern and Yorke NRM Regional Summary 2008
The creek was given a Very Poor rating at this site because the ecosystem showed evidence of major changes to both the animal and plant life, and a significant breakdown in the way the ecosystem functions because of human impact. Nutrient enrichment and fine sediment deposits had both contributed to the very poor condition of this site, which was also significantly affected by prolonged drought.
The channel was mostly dry when the site was sampled in November 2008, with only a few small, isolated rock pools present, which provided limited habitat for a low diversity of 24 macroinvertebrate species. The most numerous species were chironomids (Chironomus) and mosquito larvae (Aedes). More than 70% of the community were forms tolerant of pollution, which feed on decaying organic material. No rare or sensitive species were found.
The water was moderately fresh (2,000 mg/L), very poorly oxygenated (1.7% saturation) and slightly coloured by tannins. It contained moderate to high concentrations of nutrients such as nitrogen (0.6 mg/L) and phosphorus (0.05 mg/L). A large amount of small algae, or phytoplankton, was growing in the water, which is another indication of nutrient enrichment.
The sediments were very anaerobic and mostly comprised large amounts of detritus, clay and silt. The banks of the creek showed considerable damage from past floods and sheep accessing the stream.
Large growths of aquatic plants such as reeds (Phragmites australis) and Cumbungi (Typha domingensis) lined the edge of the pools, which were densely shaded by the surrounding hills and riparian vegetation.
Introduced pine trees and native gum trees grew over introduced grasses in the riparian zone. Further afield were paddocks that were grazed by sheep.
Special environmental features
Pressures and management responses
|Livestock have direct access at the site and upstream, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds).||A review of the River Management Plan for the Wakefield Catchment by the Northern and York NRM Board is currently underway.|
|Limited riparian zone vegetation at the site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).|
|Large nutrient inputs from numerous diffuse sources in the catchment (leading to extensive growth of algae and aquatic weeds).|
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