Tatiara Creek, Bordertown
2009 Aquatic Ecosystem Condition Report
- Permanently wet channel in autumn and spring 2009.
- Sparse macroinvertebrate community with no rare or sensitive species.
- Obvious signs of nutrient and organic enrichment.
- Riparian vegetation limited to a narrow zone of River Red Gums over introduced grasses.
- Large deposit of fine sediment in the channel.
About the location
Tatiara Creek is a moderately sized stream in the upper South East with a catchment area over 430 km2. It rises in western Victoria in the Lillimur area and flows in a westerly direction through Bordertown and Poocher Swamp before disappearing underground several kilometres west of Bordertown. The major land uses are grazing and cropping, and the stream also receives urban stormwater as it traverses through Bordertown.
The monitoring site was located in a small recreational roadside park just upstream from the Dukes Highway in Bordertown.
The creek was given a Very Poor rating because the site sampled showed evidence of major changes in ecosystem structure and a significant breakdown to the way the ecosystem functions. There was considerable evidence of human disturbance, including organic enrichment of the sediments, high nutrient levels, poor riparian habitat and large silt deposits in the channel.
A sparse community of about 17 species of macroinvertebrates was collected from the channel that ranged from 7–9 metres wide and extended over 95 centimetres deep, in autumn and spring 2009. The community was dominated by corixid waterbugs (Micronecta) and included a range of other generalists and species tolerant to poor water quality such as limpets, snails, worms, crustaceans, fly larvae and waterbugs. The community included rat-tailed maggots, which are the larvae of a type of fly that generally only occurs in highly polluted waters with a large organic load. No sensitive or rare species were found.
The water was moderately fresh (salinity ranged from 1,070–1,723 mg/L), moderately to well oxygenated (49–64% saturation) and turbid, with high concentrations of nutrients such as nitrogen (1.2–1.4 mg/L) and phosphorus (0.1 mg/L).
The sediments were dominated by silt, detritus, sand and clay; samples taken from below the surface were blackened, sulfidic and anaerobic, or lacking in oxygen. A large deposit of fine silt over 10 centimetres thick was deposited in the middle of the channel.
The only aquatic plant growing in the channel and on the water’s edge was a few clumps of cumbungi (Typha). Large growths of phytoplankton were recorded during both seasons sampled but filamentous algae was not detected during 2009.
The riparian zone was less than five metres wide and consisted of River Red Gums over introduced grasses lining both sides of the creek. The surrounding vegetation at the site was an urban recreational park.
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 South East NRM Board supports targeted projects that provide opportunities for landholders to access grants for fencing for stock exclusion from time to time for priority catchments.|
|Limited riparian zone vegetation at the site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).||The South East NRM Board assists landholders to access targeted grant opportunities for revegetation and ecosystem protection when funding is available. The Board also works closely with landholders consistent with the Board’s Regional Pest Management Plan to control weeds on their property and to assist in halting their spread to other properties.|