North Para River, 4.5 km north-west from Eden Valley
2011 Aquatic Ecosystem Condition Report
- Permanently wet, moderately fresh, slow-flowing stream in autumn and spring 2011
- Sparse macroinvertebrate community with no rare or sensitive species
- Obvious signs of moderate to gross nutrient enrichment
- Riparian vegetation dominated by introduced grasses, weeds, sedges and rushes under a few gum trees
- Fine sediment deposited in the channel
About the location
The North Para River is a large stream in the Southern Mount Lofty Ranges that rises south from Kaiserstuhl Conservation Park and flows north towards Angaston, then turns west towards Nuriootpa and finally turns south-west, where it eventually joins with the South Para River to form the Gawler River in Gawler. The monitoring site was located near a track off Mirooloo Road, about 4.5 km north-west from Eden Valley. The major land uses in the 1,220 hectare catchment are stock grazing and irrigated vines, with smaller areas used for hay production, remnant native vegetation and rural residential living.
The river 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, degraded riparian habitats and fine sediment deposition in the channel.
A sparse community of at least 25 species of macroinvertebrates was collected from the slow-flowing stream, 3-4 metres wide and up to 42 cm deep, in autumn and spring 2011. The community was dominated by species tolerant to poor water quality such as mites, waterbugs (Micronecta) and amphipods. It also included smaller numbers of snails, freshwater shrimp, yabbies, beetles, mosquitoes, chironomids, mayflies, odonates and caddisflies. No sensitive or rare species were collected. The only flow-dependent species observed were a few chironomids from the genus Rheotanytarsus that inhabited the small area of riffle that was present in spring.
The water was moderately fresh (salinity ranged from 1,292-1,421 mg/L), well oxygenated (78-80 % saturated), slightly coloured, and with moderate to high concentrations of nutrients such as nitrogen (1.3-1.9 mg/L) and phosphorus (0.05-0.08 mg/L).
The sediments were dominated by bedrock, algae and detritus, with sand, silt and clay also present. Samples taken from below the surface appeared well oxygenated in autumn but were black and sulfidic in spring, when the sediments were anaerobic and lacked oxygen. A large deposit of silt, 1-5 cm deep, covered the streambed in spring. No significant erosion was noted during either survey in 2011.
No evidence of filamentous algae was seen in autumn but over 10% of the channel was covered with Cladophora in spring. Aquatic plants extended over about 10% of the site, including patches of submerged (Myriophyllum) and emergent species (Cyperus, Cotula, Juncus and Rumex). The riparian vegetation consisted of a few River Red Gums over sedges, rushes and a range of introduced grasses and weeds. The surrounding vegetation was cattle grazing land with a few scattered gum trees over introduced grasses.
Special environmental features
The presence of permanently wet, slow-flowing habitats was the most notable feature of this site on the North Para River.
Pressures and management responses
|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.|
|Large nutrient inputs to the creek from numerous diffuse sources (leading to extensive growth of algae and aquatic weeds)||The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes working with industry and landholders to ensure efficient use of fertilisers and discuss ways to reduce runoff of nutrients into waterways.|
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.