Riparian vegetation limited to introduced grasses.
Minor bank erosion due to stock damage and large silt deposits present in the channel.
Area map
About the location
Reedy Creek–Mount Hope Drain is a moderately sized drain in the lower South East with a catchment area of about 460 km2. Reedy Creek rises between Kalangadoo and Mount Burr and flows in a north-west direction to Furner, where water can be diverted south-west into the Reedy Creek–Mount Hope Drain. This drain flows into Mullins Swamp and during wet periods, water may flow out of this wetland into Lake Frome and then eventually discharge into Rivoli Bay at Southend. The major land uses are grazing and cropping, although there are also patches of remnant native vegetation in conservation parks and swamps and some forestry in the upstream catchment.
Reedy Creek–Mount Hope Drain is an artificially constructed drain where the primary function is to remove surface water and draining saline groundwater to improve agricultural productivity in the region (Department for Water 2010). Given its artificial character, the drain is not expected to be in a highly rated aquatic ecosystem condition, although it does provide significant habitat for many aquatic species in the region.
The monitoring site was located in the lower reaches before the drain enters Mullins Swamp, at the gauge station on Range Road, about seven kilometres north–north–east of Southend.
The drain was given a Poor rating because the site sampled showed evidence of major changes in ecosystem structure and moderate changes to the way the ecosystem functions. There was considerable evidence of human disturbance, including nutrient enrichment and poor riparian habitat.
Findings
A sparse community of about 27 species of macroinvertebrates was collected from the slow-flowing channel, 10–12 metres wide and up to 52 centimetres deep, in autumn and spring 2009. The community was dominated by generalists and species tolerant to poor water quality such as hydrobiid snails, chironomids, planorbid snails (Glyptophysa) and amphipod crustaceans. The only regionally uncommon species recorded was a giant waterbug (Diplonychus), and no rare or sensitive species were collected.
The water was fresh to moderately fresh (salinity ranged from 718–1,190 mg/L), well oxygenated (147–176% saturation) and clear, with moderate to high concentrations of nutrients such as nitrogen (0.78–1.18 mg/L) and phosphorus (0.01–0.03 mg/L).
The sediments were dominated by algae, detritus and silt, with smaller amounts of cobble, sand and clay also present; samples taken from below the surface were blackened, sulfidic and anaerobic, or lacking in oxygen. Some minor bank erosion caused by stock damage was noted and a large deposit of fine silt was present in the middle of the channel.
A range of submerged (Chara) and emergent plants (Juncus, introduced Rorippa and Triglochin striatum) was growing in the channel and on the water’s edge. These plants covered between 65–90% of the channel in autumn but reduced to less than 65% in spring when the cover of filamentous algae had increased over 10–35% of the drain.
The narrow riparian zone lacked any native species and consisted of introduced grasses. The surrounding vegetation at the site was grassland.
Special environmental features
Reedy Creek-Mount Hope Drain provides habitat for the threatened Southern Pygmy Perch and a more common species of fish called the Common Galaxias (M Hammer, Native Fish Australia SA, 2004), although neither were seen in 2009.
Pressures and management responses
Pressures
Management responses
Livestock having direct access (causing sediment erosion and adding excessive nutrients).
Drains have been constructed since the 1860s as an engineering solution to support agricultural development and it is South Eastern Water Conservation and Drainage Board practice to lease drain reserves for grazing in certain circumstances. Not all drains are subject to grazing and leases for grazing are only approved following an engineering and environmental assessment. Lease conditions require the lessee to fulfil pest plant, pest animal and CFS management requirements, thereby relieving the Board of these responsibilities.
Limited riparian zone vegetation (reducing habitat quality, increasing sediment erosion).
The South Eastern Water Conservation and Drainage Board has undertaken a limited revegetation program at key locations, and has the ability to undertake further revegetation works when resources allow. Revegetation at biological hotspots is recognised as a mechanism to reduce nutrient input and soil erosion, and can be undertaken if it does not impede access for management and maintenance.
Observed Condition
Expected Condition
