Adelaide and Mount Lofty Ranges NRM Regional Summary
2013 Aquatic Ecosystem Condition Report
Forty-six sites were sampled from the region during autumn and spring 2013. They were located from the Gawler River catchment in the north to Hindmarsh River on the Fleurieu Peninsula in the south. Land-use was dominated by agriculture (stock grazing and cereal cropping) and residential living, with patches of remnant native vegetation largely confined to conservation parks, steep hills, gullies, along creeklines and as part of roadside vegetation.
- 26% of sites were assigned to the Very Good or Good condition ratings whereas the remaining 74% of sites were either in Fair, Poor or Very Poor condition; no sites were assessed to be in Excellent condition
- The most significant streams were located in the high rainfall, high altitude and more vegetated parts of the region (eg First, Sixth, Brownhill, Scott and Jacobs creeks, and Little Para River in the Southern Mt Lofty Ranges and First, Deep, Callawonga and Boat Harbour creeks on the Fleurieu Peninsula)
- The better streams were distinguished by the presence of several rare, sensitive and flow dependent macroinvertebrates and showed evidence of low to moderate nutrient enrichment
- The other streams were generally located in more developed agricultural and urbanised areas and showed evidence of significant nutrient enrichment, typically had moderate to high salinity, most had limited and highly degraded riparian habitats, channels were often covered in fine sediment, and they frequently supported pest plants and fish
- The poorer streams lacked rare and sensitive species and were dominated by generalists and tolerant macroinvertebrates
- Riparian habitats of most streams in the region were degraded due to the presence, and often dominance, of weeds and introduced grasses in the understorey vegetation
Sites monitored in the Adelaide and Mount Lofty Ranges region during 2013 were considered to be in a Very Good to Very Poor condition. No sites were assigned to the Excellent condition class and given the scale of vegetation clearance and nutrient enrichment evident in 2013 (and sampled in past years) it is unlikely that any stream in the region remains unaffected by human activities. Of the sites assessed, two sites (4%) were in Very Good condition with little change to animal and plant life; 10 sites (22%) were considered to be Good condition with only minor changes to animal and plant life; 14 sites (30%) were in Fair condition with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned; 18 sites (39%) were in Poor condition with evidence of major changes in animal and plant life, and moderate changes to the way the ecosystems functioned; and 2 sites (4%) were Very Poor with evidence of major changes in animal and plant life, and the way the ecosystems functioned.
The better sites were located in high rainfall catchments (>600 mm annual rainfall) from the Fleurieu Peninsula (eg First Creek, The Deep Creek, Callawonga Creek and Boat Harbour Creek) and Southern Mount Lofty Ranges (eg First Creek, Sixth Creek, Brownhill Creek, Scott Creek, Jacobs Creek, and a site on the Little Para River upstream from the reservoir. These sites were characterised by their moderately diverse to diverse macroinvertebrate communities, presence of several rare, sensitive and/or flow-dependent species, they had well vegetated riparian zones, and most had low to occasionally moderate nutrient concentrations when sampled in 2013.
In contrast, the worst sites were from largely cleared catchments with degraded riparian habitats that lacked any significant patches of native vegetation. They included an ephemeral tributary of Yankalilla River that was dry in both seasons sampled, and Walker’s Creek that had few aquatic macroinvertebrates present and showed evidence of damage caused by high salinity, nutrient enrichment and smothering by fine sediment.
The sites assigned to either the Fair or Poor ratings showed evidence of significant nutrient enrichment (eg high nutrient concentrations, large growths of algae and/or aquatic plants, anaerobic sediments) but were distinguished by the number of rare and sensitive species and extent of damage to the riparian zone. The Fair sites tended to occur in streams with more extensive riparian habitats and some remnant native vegetation in their catchments and included many of the larger streams in the Adelaide Hills (eg Sturt, Onkaparinga and North Para rivers). The Poor sites included streams receiving significant runoff from agricultural and urban land uses, including parts of several major (e.g. Torrens, North Para and South Para rivers) and numerous smaller (eg Aldgate, Cox, Inverbrackie, Millers and Greenock creeks) streams from the Adelaide Hills, and a few coastal streams from the Fleurieu Peninsula (eg Bungala River and its’ tributaries, and Back Valley Creek).
The aquatic macroinvertebrate communities of most streams were typically dominated by a small number of very tolerant species and included low numbers of rare and sensitive species. The amphipod crustacean (Austrochiltonia) was usually the most abundantly collected macroinvertebrate along with chironomids (including Paramerina, Procladius, Cricotopus, Paralimnophyes, Tanytarsus, Chironomus, Dicrotendipes and Polypedilum). Where flowing water was present, large numbers of blackfly larvae (Austrosimulium furiosum and Simulium ornatipes), chironomids (Rheotanytarsus), mayflies (Atalophlebia and Thraulophlebia) and caddisflies (Cheumatopsyche) were often recorded. The slow to non-flowing pools usually provided habitat for waterbugs (Micronecta, Microvelia and Anisops), beetles (Sternopriscus, Necterosoma, Platynectes and Scirtidae), yabbies (Cherax destructor), shrimp (Paratya), introduced snails (Physa and Potamopyrgus), mosquitoes (Aedes, Anopheles and Culex), biting midges (Bezzia and Culicoides), mayflies (Cloeon and Tasmanocoenis), caddisflies (Lectrides and Triplectides australis), stoneflies (Dinotoperla evansi) and flies from the Family Dixidae. Low numbers of a range of worms, mites, dragonflies and damselflies were also found at most sites.
Streams that flow provided more habitat complexity and supported a wider range of aquatic species than those that ceased to flow or dried up for at least part of the year. A range of rare and sensitive species that frequent freshwater flowing riffle habitats were collected from the better sites, including stoneflies (Illiesoperla mayii and Newmanoperla thoreyi), mayflies (Offadens, Centroptilum and Tasmanophlebia), dragonflies (Hemigomphus gouldii and Austrogomphus guerini), caddisflies (Taschorema, Ulmerochorema, Oxyethira, Orphninotrichia, Lingora and Atriplectides), beetles (Simsonia), blackflies (Paracnephia and Simulium melatum), thaumaleid flies (Austrothaumalea) and a chironomid (Riethia). These streams also occasionally provided habitat for State-listed threatened fish, including Mountain Galaxias (Galaxias olidus) and Climbing Galaxias (Galaxias brevipennis).
Most streams in the region were distinguished by the presence of a single line of River Red Gums or weedy willows or ash trees on the banks, over introduced grasses and weeds. The few streams with more extensive riparian zones were generally located in conservation parks or hilly country where most of the overstorey was dominated by native trees and shrubs but in most cases the understorey had still been invaded by weeds and introduced grasses.
The median water quality data from sites sampled during 2013 indicated that streams from the Western Mt Lofty Ranges were generally fresh (salinity of about 725 mg/L), well oxygenated (>100% saturation and 9 mg/L), alkaline (pH>7) and enriched with nutrients such as nitrogen (>0.9 mg/L) and phosphorus (0.05 mg/L).
Special environmental features
Many rare and sensitive macroinvertebrates were found in 2013, including mites (Family Oxidae), stoneflies (Riekoperla naso and Austrocerca tasmanicum), and the above-listed flow-dependent species that were collected from the better streams in the Adelaide Hills and Fleurieu Peninsula.
A number of species were not collected during this sampling period but had been recorded from the region in 2011, including several chironomids (Harrissius, Apsectrotanypus, Stempellina and Harnischia) and caddisflies (Anisocentropus, Triplectides similis and members of the Family Tasimiidae), a mayfly (Nousia fuscula) and a beetle called a waterpenny (Sclerocyphon). Given the lack of any recent land use changes or significant disturbances caused by fire or drought over this time period, these species probably still occur in small reaches of the less disturbed streams in the region.
Two threatened species of fish were recorded from the better streams in the region during 2013, including the Mountain Galaxias and Climbing Galaxias. Several other significant fish have also been recorded from a number of coastal streams in the region during recent fish surveys, including Southern Pygmy Perch, Congolli, Freshwater Catfish and various eels and lampreys (Hammer et al. 2009).
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.|
|Stormwater runoff containing high nutrient and sediment loads discharging to the creek (causing habitat disturbance, algal growth and aquatic weeds).||The Adelaide and Mount Lofty Ranges NRM Board has a well developed stormwater quality improvement, harvesting and reuse program which has installed (and maintains) gross pollutant (and silt) traps in several watercourses across the region to catch litter, debris and silt in order to minimise impacts and damage to seagrass in the receiving marine environment. Stormwater captured is also treated through artificial wetlands across the region which act as suspended solid and nutrient filters; these wetlands also provide important habitat for many native species.|
|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.|
|Saline groundwater inflows to the creek (reducing ecological integrity).||The Adelaide and Mount Lofty Ranges NRM Board has installed telemetered groundwater monitoring stations at key locations within the region. These are monitored for level and salinity; unusual results (such as high salinity influxes) are investigated.|
|Failing onsite wastewater treatment systems in the catchment, adding nutrients through shallow subsurface flows or overland flows to creeks (leading to algal growth).||Failing onsite wastewater treatment systems in the Mount Lofty Ranges Watershed are being addressed by improving maintenance of existing systems, upgrading to a more effective system, or via connection to a local government Community Wastewater Management Systems or to an SA Water sewer network, where these are available. The Mount Lofty Ranges Waste Control Program is addressing failing onsite systems by identifying and facilitating upgrades. This effective program is being delivered by the Adelaide Hills Council in partnership with the AMLR NRM Board, SA Water, Department of Health and the EPA.|
|Wastewater discharges to the creek, adding excessive nutrients and organic matter (leading to algal growth and aquatic weeds).||
SA Water Wastewater Treatment Plants at Hahndorf and Heathfield
SA Water assess and undertake scheduled process improvement actions at wastewater treatment plants, with the aim to reduce environmental risk and ensure operations are compliant with EPA licence conditions.
This aquatic ecosystem condition summary 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.