Broughton River, Koolunga
2008 Aquatic Ecosystem Condition Report
- Affected by nutrient enrichment and fine sediment.
- Extensive growths of aquatic plants.
- Riparian zone invaded by weeds.
- The river provides habitat for vulnerable and notable species.
- Site dry at time of inspection in December 2008.
About the location
Broughton River rises east of Farrell Flat in the Mid North of the state. It flows northeast towards Spalding and then west through Yacka, Redhill and Merriton before discharging into Spencer Gulf, south of Port Pirie. Livestock grazing and cereal cropping are the main land uses in the upper catchment of the river, where there is also some forestry plantations and urban development along tributary streams such as Hill River, Hutt River and Bundaleer Creek. The site selected for monitoring lies in the mid to lower reaches of the river, off Koolunga-Brinkworth Road, just a few hundred metres south of the Koolunga township.
The river was given a Fair rating at this site because the ecosystem showed evidence of moderate changes to animal and plant life, and some changes to the way the ecosystem functions. Evidence suggested high loads of nutrient and sediment were deposited into the stream in wetter seasons; it is likely a poorer grade may have been given if the river had been flowing when it was inspected.
No water was available for sampling and testing when the site was visited in December 2008. The channel was covered with dense stands of Common Reed (Phragmites australis) and sedges (Cyperus gymnocaulos and Schoenoplectus pungens).
River Red gums, wattles, Spiny Sedge, and introduced Pepper Trees and grasses dominated the riparian zone, as well as weeds such as thistles, boxthorn and Tobacco Trees. The vegetation was up to 40 metres wide in places along the river, however few trees remained in the surrounding area which was used for cereal cropping.
Special environmental features
Broughton River is notable because it provides habitat for polychaete worms (bristle worms); macroinvertebrates normally associated with marine and estuarine conditions. The river mouth also provides refuge for the vulnerable Krefft's Black Tiger Snake.
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 Broughton 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).|
|Extensive weed growth in the riparian zone at the site and upstream (causing habitat disturbance).|
|Gully erosion upstream in the catchment (causing habitat disturbance).|