North Para River, 4 km north from Angaston
2011 Aquatic Ecosystem Condition Report
- Permanently wet, flowing, freshwater stream in autumn and spring 2011
- Diverse macroinvertebrate community with some rare and sensitive species
- Obvious signs of moderate to gross nutrient enrichment
- Riparian vegetation dominated by introduced grasses and a few gum trees.
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 on a track off Kalimna Road, about 4 km north from Angaston. The major land uses in the 11,507 hectare catchment are stock grazing, irrigated vines and hay production, with smaller areas used for a range of other agricultural activities, residential living and remnant native vegetation.
The river 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, degraded riparian vegetation, fine sediment deposition and areas with bank erosion. Despite this the stream still provided habitat for some rare and sensitive macroinvertebrate species.
A diverse community of at least 51 species of macroinvertebrates was collected from the flowing river, 4.4-5.2 wide and up to 55 cm deep, in autumn and spring 2011. The river comprised fast-flowing riffle habitats and slow to non-flowing edge habitats along the main channel in both seasons sampled. The community was dominated by large numbers of generalists and species tolerant to poor water quality such as amphipods, small baetid mayflies and blackflies. It also included smaller numbers of flatworms, limpets, introduced and native snails, worms, mites, freshwater shrimp, springtails, beetles, mosquitoes, biting midges, soldierflies, chironomids, leptophlebiid mayflies, waterbugs, odonates, stoneflies and caddisflies. A few rare and sensitive rare species were also recorded, including a mayfly (Atalophlebia australis) and two stoneflies (Riekoperla naso and Austrocerca tasmanica). Several species normally associated with flowing habitats were also collected, including a dytiscid beetle (Platynectes decempunctatus), blackfly (Simulium ornatipes) and the above-listed rare and sensitive species. No fish were seen at the site in 2011.
The water was moderately fresh (salinity ranged from 1,241-1,790 mg/L), well oxygenated (72-110% saturated), clear, and with moderate to high concentrations of nutrients such as nitrogen (0.68-1.17 mg/L) and phosphorus (0.05 mg/L).
The sediments were dominated by detritus, cobble, algae and silt in the slower flowing sections and cobble, boulder and detritus in the fast-flowing riffles. Samples taken from below the surface were slightly blackened in appearance but otherwise showed no evidence that the sediments had recently been anaerobic or lacking in oxygen. A large deposit of silt, 1-5 cm deep, covered parts of the riverbed in spring and about 10 m of bank showed signs of erosion due to recent flood damage.
A large growth of filamentous algae (mostly Cladophora and Spirogyra) covered over 35% of the river in spring. Aquatic plants covered more than 35% of the channel in autumn but only extended over 10% of the site in spring. Both submerged (Chara and Callitriche) and emergent species (Cyperus, Phragmites, Rumex, Triglochin, Typha, Bolboschoenus, Juncus and Schoenoplectus) were recorded during 2011. The riparian vegetation was dominated by introduced grasses and weeds under some scattered River Red Gums and wattles. The surrounding vegetation was mostly cleared sheep grazing land with a few isolated gum trees in the local landscape.
Special environmental features
The North Para River near Angaston provides regularly flowing, freshwater habitats that support a diverse assemblage of aquatic species, including a few rare and sensitive types of macroinvertebrates.
Pressures and management responses
|Insufficient natural water flows in the creek resulting from water extraction and climate variability (reducing ecological integrity).||Through water allocation planning the Adelaide and Mount Lofty Ranges NRM Board seeks to manage a sustainable water supply for the region so that there is enough water available for everyone (including the environment) even in drought conditions.|
|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.|
|Livestock having direct access at the site and upstream (causing sediment erosion and adding excessive nutrients).||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 waterway and wetland fencing to exclude or limit stock from entering riparian zones.|
|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.