Riparian vegetation consists of a few paperbark trees over introduced grasses.
Moderate amount of silt deposited in the channel.
Area map
About the location
Kingston Main Drain is a small drain in the lower South East with a catchment area over 100 km2. It rises south-east of Kingston SE and flows in a north-westerly direction into the Maria Creek estuary in Kingston SE. The major land use is grazing with small patches of remnant native vegetation in the catchment.
Kingston Main 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 upper catchment near Salt Well Road, about 17 km south-east of Kingston SE.
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 aquatic and riparian habitat structure.
Findings
A sparse community of about eight species of macroinvertebrates was collected from isolated pools, over seven metres wide and 37 centimetres deep, in spring 2009; the drain was dry in autumn. The community was dominated by generalists and species tolerant to poor water quality such as amphipod crustaceans, dytiscid beetles and chironomids. Most of the community consisted of highly mobile, aerially dispersed insects. No sensitive or rare species were found.
The water was moderately fresh (salinity of 2,990 mg/L), well oxygenated (127% saturation) and clear, with moderate to high concentrations of nutrients such as nitrogen (2.12 mg/L) and phosphorus (0.05 mg/L).
The sediments were dominated by algae, silt and detritus, and included a small amount of boulder, pebble and silt; samples taken from below the surface were blackened, sulfidic and anaerobic, or lacking in oxygen. More than one centimetre of fine silt was deposited in the channel.
A sedge (Cyperus) was the only higher plant growing in the channel and on the water’s edge. However, more than 65% of the site was covered by a large growth of filamentous algae, highlighting the obvious nutrient enrichment of this drain.
The narrow riparian zone consisted of a few scattered paperbark trees (Melaleuca) over introduced grasses. The surrounding vegetation at the site was low paperbark woodland over introduced grasses.
Special environmental features
The drain provides habitat for a type of salt tolerant fish called the Small-mouthed Hardyhead.
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
