Drain M, near Callendale
2014 Aquatic Ecosystem Condition Report
- Dry drain in autumn and spring 2014
- Likely to be nutrient enriched when water is present due to the surrounding land uses
- Riparian vegetation limited to weeds and introduced grasses
- No significant change since last sampled in 2009.
About the location
Drain M is a large drain in the South East with a catchment area of almost 4000 square kilometres. It rises near Edenhope in Victoria, as Mosquito Creek and flows west into Bool Lagoon. Drain M then arises from Bool Lagoon, flows in a south-westerly direction and receives drainage from Sutherland Drain, Mount Hope Drain, Reedy Creek M Drain, Bellinger Swamp Drain, Baker Range Drain and Drain C, and ultimately discharges into Lake George, near Beachport.
Drain M is an artificially constructed drain where the primary function is to remove surface water 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 major land uses are grazing and cropping with some areas of vineyards and native vegetation. The monitoring site was located upstream of Cluain Lane, just south of Callendale and about 30 kilometres south from Lucindale.
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 poor habitat in the riparian zone and limited remnant vegetation remaining in the surrounding landscape.
The 25 metre wide drain was dry in both autumn and spring 2014 so macroinvertebrate and water quality data were not available.
The sediments were dominated by detritus with smaller amounts of sand, clay, bedrock, boulder, cobble and pebble also present; samples taken from below the surface comprised limestone and appeared to be aerobic but probably become blackened and anaerobic when wet due to decomposition of the organically enriched sediments. No significant areas of bank erosion were seen but sheep droppings were deposited throughout the channel and banks of the drain.
No aquatic plants were growing in the channel and terrestrial grasses and weeds were the only plants recorded from the banks, suggesting it has been a long time since this section of drain contained enough water to support the growth of water plants. The surrounding vegetation at the site was sheep and cattle grazing land with scattered large gum trees and some small areas with horticultural cropping.
Special environmental features
None detected at the site sampled in 2014, although the lower reaches of this drain provides significant, permanently wet habitat that supports a number of threatened species, including both fish (Yarra Pygmy Perch and Southern Pygmy Perch) and frogs (Southern Bell-frog).
Pressures and 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.|