Every stream in the region has been significantly altered since European settlement as a result of clearing native vegetation for agriculture. Every site sampled showed evidence of nutrient enrichment such as large algal growths and excessive growths of reeds and other aquatic plants, particularly wherever the stream channel was directly exposed to sunlight. Most streams sampled in the region had high salinity levels (> 3,000 mg/L), and severely degraded riparian zones, invaded by introduced grasses and weeds, with cropping often occurring right up to the edge of the stream.
Seven sites were assigned either a Fair or Poor rating because their ecosystems showed evidence of moderate to major changes to animal and plant communities, and at least some changes to the way each ecosystem functioned. Most streams had salinities in the 3,000–9,000 mg/L range which is too high for the majority of freshwater macroinvertebrate species to tolerate. The Rocky, Light and Wakefield rivers, and Freshwater Creek were dominated by saline tolerant species that thrive in algal covered streams.
Three streams were dry at the sites inspected but still showed substantial evidence of nutrient enrichment, including the Broughton River at Koolunga, Eyre Creek and Gilbert River at Stockport.
The eighth site sampled in the region, at Skillogallee Creek, was given a Very Poor rating because the ecosystem showed evidence of major changes to both the animal and plant life, and a significant breakdown in the way the ecosystem functioned because of grazing and drought effects.
No rare or sensitive species were found at the sites sampled in spring 2008.
Only a few streams in the region have provided habitat for rare and sensitive macroinvertebrate species in the past. The most significant is Mary Springs, located on an unnamed stream that flows into Beetaloo Reservoir in the Crystal Brook and Broughton River catchments. It supported a wide range of notable species, including a stonefly (Dinotoperla evansi), mayflies (Atalophlebia, Nousia fuscula, Offadens), and various caddisflies (e.g. Orphninotrichia maculata and Apsilochorema gisbum) that are more typically found in the cooler and wetter streams from the southern Mount Lofty Ranges.
The Broughton River and lower Rocky River are also known to provide habitat for bristleworms from the family Syllidae, and the upper Skillogallee Creek provided habitat for mayflies (Atalophlebia australasica and Koorrnonga inconspicua) and a caddisfly (Taschorema evansi) during the 1990's.
