Harrison Creek, near Tungkillo
2008 Aquatic Ecosystem Condition Report
- Significantly affected by nutrient enrichment, fine sediment and possibly salinity.
- Excessive growths of aquatic plants.
- Creekbanks extensively eroded and limited riparian zone with little native vegetation remaining.
- Creek dry at time of inspection in November 2008.
About the location
A small stream in the eastern Mount Lofty Ranges, Harrison Creek rises about three kilometres northeast of Mount Pleasant and flows south to join Baker Creek, which then forms into Reedy Creek south of Palmer. Livestock grazing and cereal cropping are the main land uses in the catchment.
The site selected for sampling was located three kilometres southeast of Tungkillo, off Ayers Road and upstream from a ford near the Adelaide to Mannum pipeline.
The river was given a Poor rating at this site because the ecosystem showed evidence of major changes in the animal community and plant life, and moderate changes to the way the ecosystem functions due to high loads of nutrients, sediment and possibly salt.
The creek was dry when it was inspected in November 2008, apart from a few very small temporary pools of rainwater that were covered by green filamentous algae (Cladophora or possibly Enteromorpha).
Up to 35% of the channel was covered with aquatic plants such as Sea Rush (Juncus kraussii), Sharp Clubrush(Schoenoplectus pungens) and Spiny Sedge (Cyperus gymnocaulos).
More than 50% of the banks were eroded due to slumping, flood damage and livestock having access to the channel.
River Red Gums grew sparsely over oats in the riparian zone, which was less than five metres wide. Cereal cropping occurred across the surrounding landscape, where few native trees remained.
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).||The SA Murray–Darling Basin NRM Board acknowledges the significant impacts that livestock have on aquatic environments and seeks to provide free technical advice and incentives to land managers for fencing and other works as funding permits. Funding incentives are limited in value and extent and require land managers to volunteer to be involved.|
|Limited riparian zone vegetation at the site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).||The SA Murray–Darling Basin NRM Board recognises that the management of riparian vegetation requires a long-term, integrated approach to achieve ecosystem benefits. The board therefore provides free technical advice on a range of topics for land managers and various incentives for works as funding permits.|
|Saline groundwater inflow (reducing ecological integrity).||Saline groundwater inflows may be exacerbated by two things; vegetation clearing and resultant increase in rainfall recharge, or the extraction of surface water reducing the dilution factor in natural saline discharge zones. The SA Murray–Darling Basin NRM Board’s Land Management Program strategically invests in salinity ‘hotspots’ by providing incentives to land managers to plant perennial pasture/fodder crops/ or revegetation to reduce recharge. The NRM Board works with various agencies to minimise any further vegetation clearing which may impact on the catchment’s water balance. The NRM Board seeks to manage and provide for environmental flows to allow natural dilution of saline waters through the development of Water Allocation Plans and Water Affecting Activity policies across the region.|