Riparian vegetation consists of introduced species with orchards and grazing pasture beyond
Area map
About the location
Cudlee Creek rises near Nitschke Hill and flows in a north-westerly direction to before discharging to the Torrens River. The major land uses in the 2010 hectare catchment are grazing pastures (47%) and residual native cover (22%). The monitoring site was located just upstream of the confluence with the Torrens River.
The creek was given a Fair rating because the site sampled showed evidence of moderate changes in ecosystem structure, and some changes to the way the ecosystem functions. There was evidence of human disturbance including nutrient enrichment and fine sediment deposition and a riparian zone dominated by introduced species. The stream provided habitat for only one sensitive macroinvertebrate species.
A moderately diverse community of at least 25 species of macroinvertebrates was collected from this connected flowing creek, approximately 4.5 m wide and 40 cm deep, in autumn and spring 2015. The site was dominated by hydrobiid snails, mosquito larvae, dytiscid and scirtid beetles, non-biting midges and mayflies. Other species collected in smaller numbers included a range of generalist and pollution tolerant species, such as flatworms, freshwater clams, round worms, mites, amphipods, fly larvae from the dixid family and waterbugs. The more sensitive mayfly species Thraulophlebia was also collected. The introduced snails Potamopyrgus and Physiella were seen at the site and yabby holes were seen in the creek bed. Frogs were heard calling at the site.
The water was fresh (salinity ranged from 441-452 mg/L), poorly oxygenated (21-38% saturation) and clear, with moderate concentrations of nutrients such as nitrogen (0.25-0.44 mg/L) and phosphorus (0.015-0.02 mg/L). The surface of the water was covered in an oily substance in autumn and iron flocculent was also seen at the site.
The sediments were dominated by silt and detritus with some clay and sand also present. Samples taken from below the surface were black clay with some silt present and showed evidence of being anaerobic, or lacking oxygen, during both autumn and spring. Deposits of silt covered the streambed to a depth of more than 10 cm in places and <10% of site was effected by bank erosion.
A small amount of phytoplankton (chlorophyll a ranged from 0.46-0.68 µg/L) was present, but no filamentous algae was seen. More than 35% of site was covered by a range of emergent plants such as Cyperus, Juncus, Polygonum, Rumex and Typha. The riparian zone consisted of willows, blackberries and other weeds and the surrounding vegetation was orchards and pasture for cattle grazing.
Widespread introduced weeds in the riparian zone at the site and upstream (reducing habitat quality).
The Adelaide and Mount Lofty Ranges NRM Board has several pest plant (weed) mitigation and control programs. They work closely with landholders to control weeds on their property and to help stop the spread to other properties and waterways.
Limited riparian zone vegetation at the creek and upstream (reducing habitat quality, increasing sediment erosion).
The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes incentives for revegetation programs around waterways and wetlands and stock exclusion as well as educating landholders about the importance of riparian vegetation in managing soil erosion.
This aquatic ecosystem condition report is based on monitoring data collected by the EPA. It was prepared with and co-funded by the Adelaide and Mount Lofty Ranges NRM Board.
Observed Condition
Expected Condition
